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1
Pamirsky, Igor Eduardovich, Alexey Grigorievich Klykov, Alexander Mikhailovich Zakharenko e Kirill Sergeevich Golokhvast. "First Data on the Differences of Phytolite Composition in Different Wheat Varieties Triticum aestivum L." Key Engineering Materials 806 (giugno 2019): 155–60. http://dx.doi.org/10.4028/www.scientific.net/kem.806.155.
Testo completoAbstract (sommario):
At current work we present first results of comparative study of the morphology and chemical composition in biomineral particles (phytoliths) of different types of wheat (Volzhskaya, Moskovskaya 39, Primorskaya 40). Optical microscopy reveals 5 morphotypes of phytolith in the stem and spike of wheat Triticum aestivum L. Although, only 3 morphotypes of phytolites were found in all three varieties, and the other 2 morphotypes were found only in some cases. These differences may be sort-specific signs. Various phytoliths have different linear sizes. As demosntrated, even within a sole type of wheat, there appears variability of the phytolitic composition. This fact may have significant implication for practical use of the phytolith analysis.
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An, Xiaohong, e Binrong Xie. "Phytoliths from Woody Plants: A Review". Diversity 14, n. 5 (26 aprile 2022): 339. http://dx.doi.org/10.3390/d14050339.
Testo completoAbstract (sommario):
Phytoliths are efficient proxies in archaeology, plant taxonomy, palaeoenvironment, and palaeoecology reconstruction, the research of which has been developing rapidly in recent years. Phytolith morphology is the basis of phytolith research. The morphological identification and classification of grass phytoliths are clear and detailed enough for application. However, the morphology of phytoliths from woody plants is ambiguous and unsystematic because of the relatively rare research on modern phytoliths and consequently seldom used in archaeology and palaeoenvironment reconstruction. This paper summarizes and concludes the research of woody phytolith morphology in the past decades. Previous studies show that palms and conifers produce some diagnostic phytoliths for identification and classification. There is progress in micromorphology, morphometry, and taxonomic identification of palms and conifers phytoliths. The phytolith morphology of broad-leaved trees is summarized according to produced parts of phytoliths in plants. The potential of further classification for broad-leaved phytoliths was discussed.
3
An, Xiaohong, e Binrong Xie. "Phytoliths from Woody Plants: A Review". Diversity 14, n. 5 (26 aprile 2022): 339. http://dx.doi.org/10.3390/d14050339.
Testo completoAbstract (sommario):
Phytoliths are efficient proxies in archaeology, plant taxonomy, palaeoenvironment, and palaeoecology reconstruction, the research of which has been developing rapidly in recent years. Phytolith morphology is the basis of phytolith research. The morphological identification and classification of grass phytoliths are clear and detailed enough for application. However, the morphology of phytoliths from woody plants is ambiguous and unsystematic because of the relatively rare research on modern phytoliths and consequently seldom used in archaeology and palaeoenvironment reconstruction. This paper summarizes and concludes the research of woody phytolith morphology in the past decades. Previous studies show that palms and conifers produce some diagnostic phytoliths for identification and classification. There is progress in micromorphology, morphometry, and taxonomic identification of palms and conifers phytoliths. The phytolith morphology of broad-leaved trees is summarized according to produced parts of phytoliths in plants. The potential of further classification for broad-leaved phytoliths was discussed.
4
Tan, Shuhui, Rencheng Li, Richard S. Vachula, Xinyue Tao, Mengdan Wen, Yizhi Liu, Haiyan Dong e Lintong Zhou. "Electron probe microanalysis of the elemental composition of phytoliths from woody bamboo species". PLOS ONE 17, n. 7 (5 luglio 2022): e0270842. http://dx.doi.org/10.1371/journal.pone.0270842.
Testo completoAbstract (sommario):
Electron probe microanalysis (EPMA) is promising for accurately determining elemental components in micro-areas of individual phytolith particles, interpreting compositional features and formation mechanisms of phytoliths in plants, identifying archeological and sedimental phytolith. However, the EPMA method of analyzing mounted slide phytoliths has not well been defined. In this study, we attempted different EPMA methods to determine the elemental compositions of phytoliths in mounted slides. Direct analysis of carbon (DAC) with other elements in phytolith could obtain abnormally high total values and carbon values. The method of carbon excluded in measuring elements (non-carbon analysis (NCA)) was feasible to obtain elemental compositions in phytolith. The NCA method was conducive to obtain the factual elemental compositions of an individual phytolith (morphotype) when the carbon content of phytolith was relatively low. The EPMA results of phytoliths from 20 bamboo species (three genera) showed that phytolith was dominantly composed of SiO2 but also included low contents of diverse other elements. The EPMA of phytoliths can provide the elemental composition of micro-areas of an individual phytolith particle. The elemental compositions of phytolith varied with their morphotypes, the genera and ecotype of bamboos. The EPMA of elemental compositions in phytoliths is a potential tool to study the formation mechanism of phytoliths, plant taxonomical identification, archaeological and paleoenvironmental reconstruction.
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Dong, Haiyan, Xiaobei Wei, Rencheng Li, Richard S. Vachula, Shuhui Tan, Lintong Zhou e Tianxi Gan. "Burned phytoliths absorbing black carbon as a potential proxy for paleofire". Holocene 32, n. 5 (4 febbraio 2022): 442–50. http://dx.doi.org/10.1177/09596836221074033.
Testo completoAbstract (sommario):
Developing and refining fire proxies is paramount for reliable reconstructions and the inferences that they gain about fire in the Earth System. Burned phytolith index is an important tool for fire reconstruction. However, the source of the darkened color which appears on burned phytoliths is controversial and requires additional study to understand the relationship between phytolith characteristics and fire activity. By simulating burning of six grass species under open conditions, we extracted phytoliths from the ashes using a microwave digestion method. Then, we measured the carbon content of the ashed phytolith and the unburned phytolith (from modern plant). Next, we measured the carbon content of burned phytolith when treated with bleach. Our results show that the carbon contents of ashed phytoliths are higher than phytoliths extracted from plants, and ashed phytoliths after bleaching. The increased carbon content probably resulted from adsorption of black carbon by phytoliths exposed to open flames. We conclude that phytolith- related carbon might be a potential indicator of paleofire using soils and sediments.
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Min, Hyun-Gi, Min-Suk Kim e Jeong-Gyu Kim. "Effect of Soil Water Contents on Arsenic Accumulation in Phytoliths of Pteris multifida and Phragmites australis". Applied Sciences 12, n. 24 (7 dicembre 2022): 12518. http://dx.doi.org/10.3390/app122412518.
Testo completoAbstract (sommario):
The accumulation of metal(loid)s in phytoliths can physically immobilize the toxic materials and reduce toxicity in plant bodies and soil. Spider brake (Pteris multifida) is a well-known As hyperaccumulator that also harbors phytolith. However, As accumulation in phytoliths has not yet been studied with P. multifida. Soil water content is considered the main factor influencing phytolith accumulation. In this study, the As concentration in the phytoliths of P. multifida was compared with that in common reed (Phragmites australis) phytoliths with various soil water content. The range of As concentration in the phytoliths of P. multifida was 414.70–1610.74 mg kg−1, and the range for P. australis phytoliths was 41.67–126.54 mg kg−1. In P. multifida, higher soil water content increased As accumulation in the phytolith but did not affect the phytolith content in the plant. In P. australis, the higher soil water content increased phytolith content in the plant but decreased As concentration in phytoliths. This study suggests that P. multifida has higher As content in phytoliths than P. australis, and this accumulation can be affected by soil water content. The current findings provide how As encapsulated in phytolith and detoxified in different plants and conditions.
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Honaine, Mariana Fernández, Alejandro F. Zucol e Margarita L. Osterrieth. "Phytolith analysis of Cyperaceae from the Pampean region, Argentina". Australian Journal of Botany 57, n. 6 (2009): 512. http://dx.doi.org/10.1071/bt09041.
Testo completoAbstract (sommario):
Cyperaceae, along with Poaceae, is the main silica accumulator. Although the anatomical-taxonomic and palaeobotanical relevance of phytoliths has been well established, there are no studies that deal with the qualitative and quantitative aspects of the phytolith production or differentiate phytoliths from the different organs in Cyperaceae. Toward the construction of a detailed database of phytolith production, we describe in the present paper the phytoliths of leaves, culms and fruits of Cyperaceae from Pampean region (Argentina). Phytoliths were extracted by a calcination technique. Qualitative and quantitative characters and percentages of phytolith morphotypes were subject to principal component analysis to analyse their taxonomic relevance. For some sedges, values of phytolith content and a comparative analysis of leaves, culms and fruit phytoliths are presented here for the first time. Diverse tissues such as epidermis, xylem, parenchyma and sclerenchyma produced phytoliths. The most abundant morphotypes were conical phytoliths, which showed differences in the base shape and in their size between organs. Leaf/culm cones have a rounded, rectangular or square base; typical fruit cones have a polygonal base and they are bigger and more robust. PCA showed that quantitative and qualitative characters of cones, along with the percentages of morphotypes, allowed group distinction.
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Aleman, Julie C., Audrey Saint-Jean, Bérangère Leys, Christopher Carcaillet, Charly Favier e Laurent Bremond. "Estimating phytolith influx in lake sediments". Quaternary Research 80, n. 2 (settembre 2013): 341–47. http://dx.doi.org/10.1016/j.yqres.2013.05.008.
Testo completoAbstract (sommario):
So far, no phytolith extraction protocols have been tested for accuracy and repeatability. Here we aim to display a phytolith extraction method combining the strengths of two widely used protocols, supplemented with silica microspheres as exogenous markers for quantifying phytolith concentrations. Phytolith concentrations were estimated for samples from two sedimentary sequences in which numerical age–depth models make it possible to calculate phytolith influxes (phytolith numbers per cm2per yr). Analysis of replicates confirmed the statistical robustness, the repeatability and the very few biases of our extraction technique for small phytoliths, since the relationship between grass silica short cells and microspheres was kept stable. Furthermore, we demonstrated that silica microspheres are robust exogenous markers for estimating phytolith concentrations. The minimum number of items (i.e., phytoliths plus silica microspheres) that must be counted to estimate phytolith concentrations and thus influxes depends on the ratio of phytoliths to microspheres (R) and is minimized when R = 1. Nevertheless, we recommend using ratios R ≤ 1 in order to avoid having the counting process become excessively time-consuming, because microspheres are easier to identify and count than phytoliths.
9
Mulholland, Susan C., e George Rapp. "Characterization of Grass Phytoliths for Archaeological Analysis". MRS Bulletin 14, n. 3 (marzo 1989): 36–39. http://dx.doi.org/10.1557/s088376940006317x.
Testo completoAbstract (sommario):
The word phytolith means “plant rocks.” Phytoliths are mineral deposits that form in and between plant cells. Any mineral deposit may be considered a phytolith, although most recent research has focused on opaline silica. Silica seems to be widespread in at least some plant families and is resistant to dissolution in a pH less than 9. Silica phytoliths therefore have the potential to be useful microfossils that can be helpful in the documentation of prehistoric environment and economy.Identifiable shapes rather than amorphous deposits are a necessary characteristic for useful microfossils. Several plant families have long been known to be consistent accumulators of identifiable silica bodies: Gramineae (grass), Cyperaceae (sedge), and Equisetaceae (horsetail). Phytoliths from the Gramineae are especially well known; specialized silica-accumulating cells produce distinctively shaped phytoliths. However, other families have also been shown to produce significant amounts of identifiable phytoliths. Ulmaceae (elm), Fabaceae (bean), Cucurbitaceae (squash), and Compositae (sunflower) are a few examples of dicotyledonous families that commonly produce phytoliths. Some families, such as the Labiatae (mint), have yielded little or no identifiable phytoliths to date. However, further study may indicate phytolith production in particular species.
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McInerney, Francesca A., Caroline A. E. Strömberg e James W. C. White. "The Neogene transition from C3 to C4 grasslands in North America: stable carbon isotope ratios of fossil phytoliths". Paleobiology 37, n. 1 (2011): 23–49. http://dx.doi.org/10.1666/09068.1.
Testo completoAbstract (sommario):
C4 grasses form the foundation of warm-climate grasslands and savannas and provide important food crops such as corn, but their Neogene rise to dominance is still not fully understood. Carbon isotope ratios of tooth enamel, soil carbonate, carbonate cements, and plant lipids indicate a late Miocene-Pliocene (8–2 Ma) transition from C3 vegetation to dominantly C4 grasses at many sites around the world. However, these isotopic proxies cannot identify whether the C4 grasses replaced woody vegetation (trees and shrubs) or C3 grasses. Here we propose a method for reconstructing the carbon isotope ratio of Neogene grasses using the carbon isotope ratio of organic matter trapped in plant silica bodies (phytoliths). Although a wide range of plants produce phytoliths, we hypothesize that in grass-dominated ecosystems the majority of phytoliths will be derived from grasses, and will yield a grass carbon isotope signature. Phytolith extracts can be contaminated by non-phytolith silica (e.g., volcanic ash). To test the feasibility of the method given these potential problems, we examined sample purity (phytolith versus non-phytolith silica), abundance of grass versus non-grass phytoliths, and carbon isotope ratios of phytolith extracts from late Miocene-Pliocene paleosols of the central Great Plains. Isotope results from the purest samples are compared with phytolith assemblage analysis of these same extracts. The dual record spans the interval of focus (ca. 12–2 Ma), allowing us, for the first time, to investigate how isotopic shifts correlate with floral change.We found that many samples contained high abundances of non-biogenic silica; therefore, only a small subset of “pure” samples (>50% of phytoliths by volume) with good preservation were considered to provide reliable carbon isotope ratios. All phytolith assemblages contained high proportions (on average 85%) of grass phytoliths, supporting our hypothesis for grass-dominated communities. Therefore, the carbon isotope ratio of pure, well-preserved samples that are dominated by grass biosilica is considered a reliable measure of the proportion of C3 and C4 grasses in the Neogene.The carbon isotope ratios of the pure fossil phytolith samples indicate a transition from predominantly C3 grasses to mixed C3-C4 grasses by 5.5 Ma and then a shift to more than 80% C4 grasses by 3–2 Ma. With the exception of the Pliocene sample, these isotopic data are broadly concordant with phytolith assemblages that show a general increase in C4 grasses in the late Miocene. However, phytolith assemblage analysis indicates lower relative abundance of C4 grasses in overall vegetation than do the carbon isotopes from the same phytolith assemblages. The discrepancy may relate to either (1) incomplete identification of (C4) PACMAD phytoliths, (2) higher production of non-diagnostic phytoliths in C4 grasses compared to C3 grasses, or (3) biases in the isotope record toward grasses rather than overall vegetation. The impact of potential incomplete characterization of (C4) PACMAD phytoliths on assemblage estimates of proportion of C4, though important, cannot reconcile discrepancies between the methods. We explore hypothesis (2) by analyzing a previously published data set of silica content in grasses and a small data set of modern grass leaf assemblage composition using analysis of variance, independent contrasts, and sign tests. These tests suggest that C4 grasses do not have more silica than C3 grasses; there is also no difference with regard to production of non-diagnostic phytoliths. Thus, it is most likely that the discrepancy between phytolith assemblages and isotope ratios is a consequence of hypothesis (3), that the isotope signature is influenced by the contribution of non-diagnostic grass phytoliths, whereas the assemblage composition is not. Assemblage-based estimates of % C4 within grasses, rather than overall vegetation, are in considerably better agreement with the isotope-based estimates. These results support the idea that, in grass-dominated assemblages, the phytolith carbon isotope method predominantly records shifts in dominant photosynthetic pathways among grasses, whereas phytolith assemblage analysis detects changes in overall vegetation. Carbon isotope ratios of fossil phytoliths in conjunction with phytolith assemblage analysis suggest that the late Neogene expansion of C4 grasses was largely at the expense of C3 grasses rather than C3 shrubs/trees. Stable isotopic analysis of phytoliths can therefore provide unique information about grass community changes during the Neogene, as well as help test how grass phytolith morphology relates to photosynthetic pathway.
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Ball, Terry B., Jack D. Brotherson e John S. Gardner. "A typologic and morphometric study of variation in phytoliths from einkorn wheat (Triticum monococcum)". Canadian Journal of Botany 71, n. 9 (1 settembre 1993): 1182–92. http://dx.doi.org/10.1139/b93-139.
Testo completoAbstract (sommario):
Variation between phytoliths produced in the laminae, inflorescence bracts, and culms of einkorn (Triticum monococcum L.) were examined. Variation in the type of phytoliths produced and in the morphometries of the various types produced was evaluated. Morphometric data were obtained using computer-assisted image analysis. Types of phytoliths produced by various plant tissues included silica cell, large and small prickle, hair cell, trichome base, stomata, sheet element, long cell, and subepidermal cell phytoliths. Laterally dendriform subepidermal cell phytoliths were unique to inflorescence tissue. Long (100–250 μm), sinuate, alate trapezoid phytoliths were unique to lamina tissue. Tukey honestly significant difference comparisons indicated that there are some significant differences (p ≤ 0.05) between the mean morphometries of silica cell phytoliths produced in the lamina tissue and those produced in the culm and inflorescence tissues. Discriminant functions based on the morphometric data obtained were effective in distinguishing between populations of silica cell phytoliths extracted from each of the plant tissue types. These results suggest that (i) when preparing reference matrial for phytolith analysis, each part of a plant should be sampled and evaluated separately, and (ii) discriminant analysis of morphometric data obtained through image analysis is a potentially valuable research tool for the further development and application of phytolith systematics. Key words: phytoliths, image analysis, Triticum monococcum.
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Lada, N. Y. "Variety of forms of phytoliths of Kulunda soils and their phytocenotic affiliation". Проблемы ботаники Южной Сибири и Монголии 22, n. 2 (4 dicembre 2023): 166–71. http://dx.doi.org/10.14258/pbssm.2023119.
Testo completoAbstract (sommario):
Phytoliths are an important component of soil and vegetation cover. Thanks to phytolith analysis, it is possible to identify vegetation cover after a long time. There is practically no information about the transition of amorphous silica in the form of phytoliths from plant mass to soil. This very important stage in the formation of the soil phytolith spectrum was considered in the works of N. K. Kiseleva. When studying the phytolith spectra of dominant grasses and sedges, she calculated the coefficient of their participation for the Mongolian steppes, and further she proposed the concept of “phytolith spectrum" In this work, we made an attempt to assess the correlation of the set of phytolith forms and their ratio in the upper soil layer with the modern composition of vegetation. For this purpose, the phytolith spectra of soils and vegetation of three ecosystems were analyzed, and the phytolith spectra of modern soils were compared. We also applied the approach of Nina Kiseleva and the results we obtained of taxonomic diagnosis of plant species based on the forms of their phytoliths. The research was carried out on the territory of the North Kulunda lacustrine-alluvial plain. The phytolith complex of the surface layer of soils of the forb-fescue with wormwood steppe is characterized by the predominance of two groups of phytoliths: truncated cone-shaped (RONDEL) phytoliths and trapezoidal wavy plates (CRENATE). In the soils of the bushy feather-grass-forb steppe and solonetzic steppe with a cereal-licorice community, trapezoidal polylobed plates (CRENATE) and bilobed particles (BILOBATE) are added to them. Other indicator forms are presented in small quantities. Calculation of the soil phytolith complex allows one to diagnose the coenotic composition of cereals of the phytolith spectrum.
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Gobetz, Katrina E., e Steven R. Bozarth. "Implications for Late Pleistocene Mastodon Diet from Opal Phytoliths in Tooth Calculus". Quaternary Research 55, n. 2 (marzo 2001): 115–22. http://dx.doi.org/10.1006/qres.2000.2207.
Testo completoAbstract (sommario):
AbstractCalculus removed from the molar teeth of four American mastodons (Mammut americanum) contained opal phytoliths which reflect major dietary components. Three samples contained abundant grass phytoliths (ca. 86% of total), with long cells and trapezoidal pooid short cells dominant (ca. 25 and 31%, respectively). Dicot phytoliths from hackberry (Celtis sp.) seeds and indeterminate deciduous trees were rare (1–3%), though well preserved, whereas phytoliths from conifer trees were not recognizable in any of the samples. Comparative analysis of calculus from modern and fossil browsers and mixed feeders implies that dicots and conifers are nearly invisible in the phytolith record. This scarcity may result from poor preservation, low silica production in woody taxa, and/or animals' selection of young, silica-poor leaves and shoots. However, abundant grass phytoliths in the mixed feeders suggest that presence versus absence of grass phytoliths may distinguish mixed feeders and grazers from browsers. Mastodons are traditionally considered browsers, but grass phytolith assemblages in three individual mastodons contained similarly high concentrations of pooids, suggesting that these grasses were a significant part of the diet. Abundant pooid phytoliths, in addition to diatoms, indicate that these mastodons grazed in a cool, moist late Pleistocene environment, possibly near water.
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Lisztes-Szabó, Zsuzsa, Anna F. Filep, Attila Csík, Ákos Pető, Titanilla G. Kertész e Mihály Braun. "pH-dependent silicon release from phytoliths of Norway spruce (Picea abies)". Journal of Paleolimnology 63, n. 1 (26 novembre 2019): 65–81. http://dx.doi.org/10.1007/s10933-019-00103-2.
Testo completoAbstract (sommario):
AbstractAccurate evaluation of the preservation state of fossil phytoliths in glacial lake sediments is important, as these microfossils are often used in paleoecological and archaeological studies. The characteristic phytolith type of the Norway spruce (Picea abies [L.] Karst.) needle is a potential keystone in paleoecological studies. In this laboratory study, we investigated dissolution of Picea abies blocky type phytoliths, to simulate dissolution processes in sediments and soils and create reference material to compare with fossil phytoliths. Intact needles, needle ash, diatomite and silica gel were treated with Britton–Robinson buffer solutions at pH values from 2 to 12 for 22 days. Silicon was measured by microwave plasma atomic emission spectrometry. Treatment effects were evaluated on longitudinal cuts of needles under a stereomicroscope and on phytolith assemblages from needles using a light microscope. Surfaces of treated phytoliths were investigated by scanning electron microscope and elemental analysis of phytoliths was determined by energy dispersive X-ray fluorescence. Dissolution of silicon in spruce needles was inhibited between pH 8.0 and 11.1. Needle tissue protects phytoliths from erosion processes at this alkaline pH range. Most dissolved silicon appeared to originate from the phytolith surfaces and the silica matrix of the apoplast in the tissues, with less from complete dissolution of phytoliths. Our experiment suggests that extraneous metal elements are incorporated into the silica structure during the dissolution process. Thus, higher element content is an effect of partial dissolution rather than a cause of dissolution. Ultrastructure of the surface of Picea-blocky type phytoliths, namely disappearance of the globular structure, may be useful to assess the intensity of destructive processes in sediments. Our experimental treatments indicate that characteristic Picea-blocky phytoliths in needles can be well-preserved, depending on circumstances in sediments. Further micro-analytical measurements will make these needles promising tools for paleoenvironmental reconstructions.
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Jattisha, P. I., e M. Sabu. "Phytoliths as a Tool for the Identification of Some Chloridoideae Grasses in Kerala". ISRN Botany 2012 (23 dicembre 2012): 1–9. http://dx.doi.org/10.5402/2012/246057.
Testo completoAbstract (sommario):
The phytoliths of eight genera including fifteen species of grasses under the subfamily Chloridoideae in Kerala were studied. Phytoliths were studied after chemical isolation. Every species was found to produce a diverse array of phytoliths. However the frequency assemblages of phytoliths, their size, and orientation in the epidermal layer appear to vary among the different species and hence can be used for the delimitation of the taxa. Consequently, an identification key following the International Code for Phytolith Nomenclature was developed for all the species studied.
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Solomonova, M. Yu, T. A. Zhembrovskaya, A. D. Lyashchenko e S. D. Kotov. "The effect of plant size on the phytoliths characteristics of short cells in the leaf epidermis of Dactylis glomerata L." Проблемы ботаники Южной Сибири и Монголии 22, n. 2 (5 dicembre 2023): 345–48. http://dx.doi.org/10.14258/pbssm.2023153.
Testo completoAbstract (sommario):
The present study is devoted to the revision of the influence of plant organs size on the size of phytoliths. Phytolith size parameters are used to identify cultivated grasses species in archaeological sites. Understanding how these characteristics are variable is necessary in such studies. The study of the variability of the phytoliths morphometric parameters will increase the possibilities of their use in plant systematics. The article presents a correlation analysis between the average values of the morphometric characteristics of Dactylis glomerata phytoliths from six different habitats with leaf sizes and generative shoots. The cock’s-foot specimens from forest, meadow and anthropogenically disturbed plant communities in the mountainous and plain parts of the south of Western Siberia were studied. Extraction of phytoliths was carried out using dry ashing. The measurement was made using the ImageJ software. Past 4.03 programs was used for statistical processing. The influence of the leaf length on the average values of the parameters of width, equivalent diameter, and inscribed radius of phytoliths of short epidermal cells of leaf was revealed. With an increase in the size of the leaf, the width of the phytolith and the parameters associated with it increase. The length of phytoliths, their area, perimeter, area and perimeter of the described figures weakly depend on the size of the vegetative organs of plants.
Key words. Crenate, Dactylis glomerata, morphometry, phytoliths, short cells.
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Hošková, Kristýna, Jiří Neustupa, Petr Pokorný e Adéla Pokorná. "Phylogenetic, ecological and intraindividual variability patterns in grass phytolith shape". Annals of Botany 129, n. 3 (29 novembre 2021): 303–14. http://dx.doi.org/10.1093/aob/mcab143.
Testo completoAbstract (sommario):
Abstract Background and Aims Grass silica short cell (GSSC) phytoliths appear to be the most reliable source of fossil evidence for tracking the evolutionary history and paleoecology of grasses. In recent years, modern techniques that quantitatively assess phytolith shape variation have widened opportunities for the classification of grass fossil phytoliths. However, phylogenetic, ecological and intraindividual variability patterns in phytolith shape remain largely unexplored. Methods The full range of intraindividual phytolith shape variation [3650 two-dimensional (2-D) outlines] from 73 extant grass species, 48 genera, 18 tribes and eight subfamilies (particularly Pooideae) was analysed using geometric morphometric analysis based on semi-landmarks spanning phytolith outlines. Key Results The 2-D phytolith shape is mainly driven by deep-time diversification of grass subfamilies. There is distinct phytolith shape variation in early-diverging lineages of Pooideae (Meliceae, Stipeae). The amount of intraindividual variation in phytolith shape varies among species, resulting in a remarkable pattern across grass phylogeny. Conclusions The phylogenetic pattern in phytolith shape was successfully revealed by applying geometric morphometrics to 2-D phytolith shape outlines, strengthening the potential of phytoliths to track the evolutionary history and paleoecology of grasses. Geometric morphometrics of 2-D phytolith shape is an excellent tool for analysis requiring large numbers of phytolith outlines, making it useful for quantitative palaeoecological reconstruction.
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Badgal, Priya, Poonam Chowdhary, Mudassir Ahmad Bhat e Amarjit Singh Soodan. "Phytolith profile of Acrachne racemosa (B. Heyne ex Roem. & Schult.) Ohwi (Cynodonteae, Chloridoideae, Poaceae)". PLOS ONE 17, n. 2 (11 febbraio 2022): e0263721. http://dx.doi.org/10.1371/journal.pone.0263721.
Testo completoAbstract (sommario):
Acrachne racemosa (B. Heyne. ex Roem. & Schult.) Ohwi of the subfamily Chloridoideae of the family Poaceae is an economically important grass species. Grasses are characterized by deposits of silica in the cells or tissues in the form of phytoliths which protect them from various types of biotic and abiotic stresses. Owing to variable shape and specificity of morphotypes, phytolith helps in taxonomical studies, reconstruction of paleoenvironments and prediction of climate changes. The present study focussed on developing a phytolith profile of the selected species. For isolation of phytolith, Dry Ashing Method was employed, and by epidermal peeling, in-situ location of phytoliths was deciphered. In the present study, silica percentage was studied from different parts of the plant and the maximum amount was found in the leaf. Frequency and morphometric data of phytolith morphotypes from different parts of the plants were also collected and analyzed. The strongest correlation was found between phytolith types of root and culm by Pearson’s correlation coefficient supported by cluster analysis. The saddle type of phytoliths had the highest frequency in the leaf; other types of phytoliths in different parts of the plant were bilobate, blocky types, elongate types, trapezoids, triangular, cross, sinuate elongate, tabular types, globular types. Functional groups and amorphous polymorphic phases of silica were also analyzed by FTIR and XRD. It was concluded that phytolith types are controlled by parts of plant body and by anatomical and environmental factors.
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Santos, Guaciara M., Anne Alexandre, Heloisa H. G. Coe, Paul E. Reyerson, John R. Southon e Cacilda N. De Carvalho. "The Phytolith 14C Puzzle: A Tale of Background Determinations and Accuracy Tests". Radiocarbon 52, n. 1 (2010): 113–28. http://dx.doi.org/10.1017/s0033822200045070.
Testo completoAbstract (sommario):
Over the past decades, analysis of occluded carbon in phytoliths (opaline silica mineral bodies that form in and between plant cells) has become a workhorse of paleoclimate and archaeological studies. Since different plant types exhibit distinctive phytolith morphologies, their assemblages are used in identifying vegetation histories or food culture adaptations. A few direct radiocarbon AMS measurements of phytoliths have been carried out, but these measurements are difficult due to the low concentrations of phytoliths in some plant species, and the small amount of C per phytolith (<2%). In addition, no phytoliths samples of a known 14C age are available to verify measurement accuracy and precision, and to check sample preparation protocols. Background corrections are also difficult to address due to the lack of suitable material. In this work, we designed a procedure to quantify a suitable blank using SiO2 powder samples (close to the opal structure, and free of 14C). The full phytolith extraction showed high carbon contamination components: a) ∼3 μg of modern C and ∼2 μg of dead C. We also performed accuracy tests on large phytolith-occluded carbon samples extracted from soils and harvested plants. The unexpected 14C ages in some of the results triggered further investigations of possible sources of carbon contamination.
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Abdul Shakoor, Sheikh, e Mudassir Ahmad Bhat. "Phytoliths as Emerging Taxonomic Tools for Identification of Plants: An Overview". Journal of Botany 2014 (29 maggio 2014): 1–9. http://dx.doi.org/10.1155/2014/318163.
Testo completoAbstract (sommario):
In the recent advancements in identification of plant species, phytoliths have found an immense role in the identification of plants at different levels of taxonomic hierarchy. Many plant groups are known to accumulate silica in solid form in and between the cells and tissues and hence create the structures commonly known as phytoliths. These phytoliths create replicas of the structures where they are deposited. The shapes of phytolith replicas, their size dimensions (morphometric parameters), surface features (ornamentation), distribution, and orientation pattern in epidermal layers of vegetative and reproductive structures as well as their frequency are highly important for characterization of species. Monocotyledonous families particularly the family Poaceae (Gramineae) are known to produce diverse phytolith types that can serve as diagnostic markers for characterization of different taxa at different levels of taxonomic hierarchy. The present paper highlights the importance of phytoliths in taxonomic analysis of plants particularly in the family Poaceae.
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Evett, Rand R., Ernesto Franco-Vizcaino e Scott L. Stephens. "Phytolith evidence for the absence of a prehistoric grass understory in a Jeffrey pine – mixed conifer forest in the Sierra San Pedro Mártir, Mexico". Canadian Journal of Forest Research 37, n. 2 (febbraio 2007): 306–17. http://dx.doi.org/10.1139/x06-240.
Testo completoAbstract (sommario):
Phytolith analysis was applied to several sites in a Jeffrey pine ( Pinus jeffreyi Grev. & Balf.) – mixed conifer forest in the Sierra San Pedro Mártir, Baja California, Mexico, to explore the hypothesis that the introduction of livestock in the late 18th century led to overgrazing of a prehistoric grass understory, resulting in changes to the prehistoric fire regime observed in the tree-ring fire-scar record. Stable soils in regions with extensive prehistoric grass cover retain a high concentration of total phytoliths and high percentage of grass phytoliths, regardless of historic vegetation changes. Phytoliths extracted from soil samples collected from several sites in the Sierra San Pedro Mártir revealed total phytolith concentrations in forest soils were generally <0.5% by mass, with most <0.1%, whereas grass phytoliths were generally <10% of the total, values consistent with the interpretation of a forest with sparse grass cover in the understory. Phytolith evidence suggests that there was minimal grass available for grazing in prehistoric Sierra San Pedro Mártir forests; overgrazing a grass understory was probably not a major driver of changes in the prehistoric fire regime.
22
Carver, Melanie R., Terry Ball, John S. Gardner e Kali M. Erickson. "SEM study of phytoliths produced by grasses indigenous to the desert experimental range in southwestern utah". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 agosto 1996): 84–85. http://dx.doi.org/10.1017/s0424820100162880.
Testo completoAbstract (sommario):
The USDA Desert Experimental Range Station located in southwestern Utah has been conducting an ongoing investigation into the effects of grazing on the ecology of the region, The study reported herein is a preliminary effort to determine if phytolith analysis can be used to gain insight into the ecology of the region prior to the 60 year period over which records have been kept.Phytoliths are solid deposits of silicon dioxide that form at specific intracellular and extracellular locations in many plant taxa. Grasses produce phytoliths with morphological characteristics diagnostic of their taxa. When a plant dies, its phytoliths resist decomposition thereby becoming micro-fossils of the plant that produced them. Micro-fossil phytoliths provide archaeobotanical and ecological information because they remain in the same soil horizon at which decay occured. In this study phytoliths produced by four grasses indigenous to the Experimental Range were analyzed. Phytoliths extracted from soil samples of different grazing treatments at the Range were then analyzed to determine if any similar to those produced by the four grasses could be identified in the soil. If so, then phytolith analysis could prove to be a viable research tool for those studying the paleoecology of the Range.
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Mercader, Julio, Tim Bennett, Chris Esselmont, Steven Simpson e Dale Walde. "Soil phytoliths from miombo woodlands in Mozambique". Quaternary Research 75, n. 1 (gennaio 2011): 138–50. http://dx.doi.org/10.1016/j.yqres.2010.09.008.
Testo completoAbstract (sommario):
AbstractThis paper describes topsoil phytolith assemblages from 25 loci underneath miombo woodlands on an eco-transect intersecting the Mozambican Rift along a geographical, altitudinal, climatic and botanical gradient. We provide the first comprehensive overview of the phytolith spectrum that defines northern Mozambique's Zambezian floristic zone. Our classifying criteria derive from comparison with previously described and quantified reference collections of trees and grasses growing in the study area. We characterize the sedimentological and soil features of the matrices where phytoliths are found, establishing correlation among geo-edaphic variables and phytoliths. Descriptive statistics along with nonparametric and parametric statistical analyses evaluate phytolith grouping criteria, variation, robustness, and membership. From a taphonomic perspective, we attest that topsoil phytolith assemblages are polygenic and do not represent an episodic snapshot of extant vegetation, but a palimpsest from plants representing various disturbance episodes, succession stages, and ecological trends. Phytoliths retrieved from Mozambican miombo soils do not seem to trace altitudinal, temperature, or precipitation gradients, and no significant differences exist between highland and lowland phytolith assemblages. This article provides a phytolith analog for woodland environments that can guide future paleoenvironmental research. It also confirms that phytolith analysis is able to detect shifts in the woodland/grassland interface.
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Octina, Rooseline Linda. "Hasil Analisis Mikrofosil Tumbuhan (phytolith) Situs Wineki dan Padang Hadoa, di Kawasan Lembah Besoa, Sulawesi Tengah." KALPATARU 26, n. 2 (30 aprile 2018): 93. http://dx.doi.org/10.24832/kpt.v26i2.317.
Testo completoAbstract (sommario):
Phytoliths are plant microfossil made of silica that varies in shape and size. Variations of form happen when silica in soil is absorbed by plants then transported and deposited in various parts of plant cells. When the plant dies, the plant's organic matter decomposes and leaves the inorganic material of silica, which we know by the name of phytoliths. Silica can survive in various environmental conditions, That’s make phytoliths are important data for scientific research including archeology. Phytoliths analysis on soil samples from prehistoric Besoa Valley’s site aimed to reveal past environmental conditions and also find out the possibility of an economical plant utilization. Extraction performed on 18 soil samples from Wineki (box K1) and the Padang Hadoa sites (box K2 and K3). Techniques were performed using Sodium Polytungstate heavy flotation. Phytoliths identification results reveal palmae plants dominate the entire site, other phytolith derived from sample are Poaeceae, Cyperaceae and also two types of economic plants Oryza and Musaceae. Difference vegetation on past (dominated by palm) and current conditions (dominated by grasses)can indicate their changing environmental conditions either due to natural or due to human intervention. The existence of Oryza and Musaceae in Padang Hadoa sites can be an indication of the use by Padang Hadoa’s prehistoric occupant.Keyword : phytolith, Besoa Valley, Oryza, Musaceae Phytoliths merupakan mikrofosil tumbuhan berbahan silica yang bervariasi secara bentuk dan ukuran. Variasi bentuk phytolith terjadi ketika silica dalam tanah terserap oleh tumbuhan kemudian terangkut dan terdeposisi pada bermacam bagian sel tumbuhan. Ketika tumbuhan mati, material organic tumbuhan membusuk dan meninggalkan material anorganik berupa silica yang kemudian kita kenal dengan nama phytoliths. Sifat silica yang dapat terawetkan diberbagai kondisi lingkungan menjadikan phytoliths data penting bagi penelitian ilmiah termasuk bagi arkeologi. Analisis phytoliths pada sampel tanah dari kawasan prasejarah Lembah Besoa ini bertujuan untuk mengungkapkan kondisi lingkungan masa lalu dan juga mengetahui kemungkinan adanya pemanfaatan tumbuhan. Ekstraksi dilakukan pada 18 sampel tanah dari Wineki ( kotak K1 ) dan situs Padang Hadoa ( kotak K2 dan K3 ). Teknik yang dilakukan yakni dengan pengambangan menggunakan mineral berat Sodium Polytungstate. Hasil identifikasi mengungkapkan tumbuhan jenis palem mendominasi seluruh situs dibandingkan dengan jenis tumbuhan lain. Jenis tumbuhan lain yang dapat diidentifikasi dari sampel yaitu jenis Poaeceae, Cyperaceae dan juga dua jenis tumbuhan ekonomis Oryza dan Musaceae. Perbedaan vegetasi di masa lalu (yang didominasi oleh palem) dan kondisi saat ini (didominasi oleh rumput ) dapat menunjukkan adanya perubahan kondisi lingkungan baik karena alam atau karena campur tangan manusia. Keberadaan Oryza dan Musaceae di situs Padang Hadoa dapat menjadi indikasi adanya pemanfaatan jenis tumbuhan tersebut oleh manusia pendukung situs Padang Hadoa ini.Kata kunci: phytolith, Lembah Besoa, Oryza, Musaceae
25
Gao, Guizai, Dongmei Jie, Lidan Liu, Hongyan Liu, Dehui Li, Nannan Li, Jichen Shi, Chengcheng Leng e Zhihe Qiao. "Assessment and calibration of representational bias in soil phytolith assemblages in Northeast China and its implications for paleovegetation reconstruction". Quaternary Research 90, n. 1 (10 aprile 2018): 38–49. http://dx.doi.org/10.1017/qua.2018.5.
Testo completoAbstract (sommario):
AbstractThe assessment and calibration of representational bias in modern soil phytolith assemblages provide the basis for improving interpretation of fossil phytolith assemblages. We studied soil phytolith representation by comparing phytoliths from living plant communities with those from paired surface soils, representing 39 plant communities in Northeast China. Together with the use of representation indices, the 34 and 30 soil morphotypes observed in forest and grassland samples, respectively, were both classified into the following four groups: “Associated types” were similarly represented in soils and in the corresponding species inventory data; “Over-represented types” and “Under-represented types” were respectively over- and under-represented in soils compared to the inventory data; and, in the case of “Special types,” the relationship with the parent plants was unclear. In addition, the diagnostic types exhibited different degrees of representation, while the most common morphotypes were equally represented between grassland samples and forest samples. On this basis, a comparison between the original and corrected soil phytolith indices of the additional 29 soil samples was conducted. The soil phytoliths frequencies corrected by R-values differed between plots with differing plant compositions, and were moderately consistent with actual plant richness in the plot inventory data. We therefore confirmed that R-values are a promising means of correcting soil phytoliths for representational bias in temperate regions. The corrected soil phytoliths can be used to reliably reflect vegetation variability. Overall, our study provides an improved understanding of soil phytolith representation and offers a potential method for improving the accuracy of paleovegetation reconstruction.
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Alexandre, Anne, Elizabeth Webb, Amaelle Landais, Clément Piel, Sébastien Devidal, Corinne Sonzogni, Martine Couapel et al. "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 16, n. 23 (5 dicembre 2019): 4613–25. http://dx.doi.org/10.5194/bg-16-4613-2019.
Testo completoAbstract (sommario):
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′18O and 17O-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′18O and 17O-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′18O and 17O-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′18O and 17O-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′18O and 17O-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 17O-excess of grass bulk phytoliths. Although under the study conditions 17O-excessPhyto 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 17O-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 17O-excess obtained from grassland phytolith 17O-excess would inform on isotope signals of several soil–plant-atmosphere processes.
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Winkler, Daniela E., Ellen Schulz-Kornas, Thomas M. Kaiser, Annelies De Cuyper, Marcus Clauss e Thomas Tütken. "Forage silica and water content control dental surface texture in guinea pigs and provide implications for dietary reconstruction". Proceedings of the National Academy of Sciences 116, n. 4 (3 gennaio 2019): 1325–30. http://dx.doi.org/10.1073/pnas.1814081116.
Testo completoAbstract (sommario):
Recent studies have shown that phytoliths are softer than dental enamel but still act as abrasive agents. Thus, phytolith content should be reflected in dental wear. Because native phytoliths show lower indentation hardness than phytoliths extracted by dry ashing, we propose that the hydration state of plant tissue will also affect dental abrasion. To assess this, we performed a controlled feeding experiment with 36 adult guinea pigs, fed exclusively with three different natural forages: lucerne, timothy grass, and bamboo with distinct phytolith/silica contents (lucerne < grass < bamboo). Each forage was fed in fresh or dried state for 3 weeks. We then performed 3D surface texture analysis (3DST) on the upper fourth premolar. Generally, enamel surface roughness increased with higher forage phytolith/silica content. Additionally, fresh and dry grass feeders displayed differences in wear patterns, with those of fresh grass feeders being similar to fresh and dry lucerne (phytolith-poor) feeders, supporting previous reports that “fresh grass grazers” show less abrasion than unspecialized grazers. Our results demonstrate that not only phytolith content but also properties such as water content can significantly affect plant abrasiveness, even to such an extent that wear patterns characteristic for dietary traits (browser–grazer differences) become indistinguishable.
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Mercader, Julio, Siobhán Clarke, Mariam Bundala, Julien Favreau, Jamie Inwood, Makarius Itambu, Fergus Larter et al. "Soil and plant phytoliths from the Acacia-Commiphora mosaics at Oldupai Gorge (Tanzania)". PeerJ 7 (11 dicembre 2019): e8211. http://dx.doi.org/10.7717/peerj.8211.
Testo completoAbstract (sommario):
This article studies soil and plant phytoliths from the Eastern Serengeti Plains, specifically the Acacia-Commiphora mosaics from Oldupai Gorge, Tanzania, as present-day analogue for the environment that was contemporaneous with the emergence of the genus Homo. We investigate whether phytolith assemblages from recent soil surfaces reflect plant community structure and composition with fidelity. The materials included 35 topsoil samples and 29 plant species (20 genera, 15 families). Phytoliths were extracted from both soil and botanical samples. Quantification aimed at discovering relationships amongst the soil and plant phytoliths relative distributions through Chi–square independence tests, establishing the statistical significance of the relationship between categorical variables within the two populations. Soil assemblages form a spectrum, or cohort of co-ocurring phytolith classes, that will allow identifying environments similar to those in the Acacia-Commiphora ecozone in the fossil record.
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Outrequin, Clément, Anne Alexandre, Christine Vallet-Coulomb, Clément Piel, Sébastien Devidal, Amaelle Landais, Martine Couapel et al. "The triple oxygen isotope composition of phytoliths, a new proxy of atmospheric relative humidity: controls of soil water isotope composition, temperature, CO<sub>2</sub> concentration and relative humidity". Climate of the Past 17, n. 5 (23 settembre 2021): 1881–902. http://dx.doi.org/10.5194/cp-17-1881-2021.
Testo completoAbstract (sommario):
Abstract. Continental atmospheric relative humidity is a major climate parameter whose variability is poorly understood by global climate models. Models' improvement relies on model–data comparisons for past periods. However, there are no truly quantitative indicators of relative humidity for the pre-instrumental period. Previous studies highlighted a quantitative relationship between the triple oxygen isotope composition of phytoliths, particularly the 17O excess of phytoliths, and atmospheric relative humidity. Here, as part of a series of calibrations, we examine the respective controls of soil water isotope composition, temperature, CO2 concentration and relative humidity on phytolith 17O excess. For that purpose, the grass species Festuca arundinacea was grown in growth chambers where these parameters were varying. The setup was designed to control the evolution of the triple oxygen isotope composition of phytoliths and all the water compartments of the soil–plant–atmosphere continuum. Different analytical techniques (cavity ring-down spectroscopy and isotope ratio mass spectrometry) were used to analyze water and silica. An inter-laboratory comparison allowed to strengthen the isotope data matching. Water and phytolith isotope compositions were compared to previous datasets obtained from growth chamber and natural tropical sites. The results show that the δ′18O value of the source water governs the starting point from which the triple oxygen isotope composition of leaf water, phytolith-forming water and phytoliths evolves. However, since the 17O excess varies little in the growth chamber and natural source waters, this has no impact on the strong relative humidity dependency of the 17O excess of phytoliths, demonstrated for the 40 %–80% relative humidity range. This relative humidity dependency is not impacted by changes in air temperature or CO2 concentration either. A relative humidity proxy equation is proposed. Each per meg of change in phytolith 17O excess reflects a change in atmospheric relative humidity of ca. 0.2 %. The ±15 per meg reproducibility on the measurement of phytolith 17O excess corresponds to a ±3.6 % precision on the reconstructed relative humidity. The low sensitivity of phytolith 17O excess to climate parameters other than relative humidity makes it particularly suitable for quantitative reconstructions of continental relative humidity changes in the past.
30
Mulholland, Susan C., George Rapp Jr. e Amy L. Ollendorf. "Variation in phytoliths from corn leaves". Canadian Journal of Botany 66, n. 10 (1 ottobre 1988): 2001–8. http://dx.doi.org/10.1139/b88-273.
Testo completoAbstract (sommario):
This paper examines variation of phytoliths in leaves of corn (Zea mays L.) as part of an ongoing project to establish accurate, reliable, phytolith "signatures." Factors investigated include leaf part, individual plant, leaf node, geographic location, and corn variety. Counts of 100 phytoliths were made on 24 separate samples, classifying shapes into dumbbell, cross, and irregular categories. Resulting assemblages were compared using chi-square and NANOVA test statistics. Results indicate that different leaf parts and corn varieties significantly affect phytolith assemblages. Base, midsection, and tip of leaf blades consistently produce different assemblages; two North Dakota native corn varieties also produce different assemblages (when part variation is eliminated). Variation due to leaf node and individual plant is not consistent; variation due to geographic location is generally not significant. It is suggested that researchers use entire leaf blade sections as samples in phytolith analysis. This sampling design will incorporate variation exhibited within the leaf blade and avoid characterization of plants by inaccurate phytolith assemblages.
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Xu, Yanyan, Caiming Shen, Min Wang, Hongwei Meng, Qifa Sun, Linpei Huang e Huiling Sun. "Modern Lacustrine Phytoliths and their Relationships with Vegetation and Climate in Western Yunnan, SW China". Forests 15, n. 7 (4 luglio 2024): 1163. http://dx.doi.org/10.3390/f15071163.
Testo completoAbstract (sommario):
As a plant kingdom and a biodiversity hotspot, Yunnan is a key region for our understanding of modern and past global changes in biodiversity and environment. As proxies of vegetation and climate, phytoliths have become increasingly important in ecological and paleoecological studies. In this study, phytolith analysis was carried out on samples of surface sediments from 70 lakes in western Yunnan, southwest China. These lakes are surrounded by modern vegetation types including broadleaved and coniferous forests, scrubs, grasslands, meadows, and alpine vegetation. The results of this study show that modern lacustrine phytoliths in western Yunnan are dominated by herbaceous phytoliths, among which Poaceae types are the most abundant. The 70 phytolith samples used can be divided into 4 groups, reflecting the major vegetation types from which samples were collected. The principal component analysis (PCA) and redundancy analysis (RDA) of the phytolith and climatic data of the 70 lacustrine phytolith samples showed that temperature and precipitation are the climatic parameters controlling the spatial distribution of phytolith assemblages in western Yunnan. Phytolith–MAT (mean annual temperature) and phytolith–MAP (mean annual precipitation) transfer functions were developed using weighted averaging partial least squares (WA-PLS), and both the MAT and MAP functions showed good performances (MAT: R2 = 0.67, RMSEP = 0.96 °C, MAP: R2 = 0.64, RMSEP = 140.4 mm). Our results also reveal that phytolith analysis is a useful technique offering reliable vegetation interpretation and climate reconstruction; thus, this study provides a basis for the vegetational and climatic interpretation of fossil lacustrine phytolith records in western Yunnan.
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Dai, Cefeng, Rui Xu, Lixia Yu, Fangwei Zhu, Maobiao Li, Juan Li, Shuguang Wang, Changming Wang e Hui Zhan. "Silicon Uptake and Phytolith Morphology in Dendrocalamus brandisii Seedling Leaf from Different Rearing Methods". Forests 14, n. 9 (15 settembre 2023): 1877. http://dx.doi.org/10.3390/f14091877.
Testo completoAbstract (sommario):
The moisture, ash, and silicon content, as well as the phytolith morphotype and concentration in the tissue-cultured, seed-cultured, and grafted seedling leaves of Dendrocalamus brandisii were determined to investigate the differences in silicon uptake and phytolith morphology in the leaves from different rearing methods. The results showed that ash, silicon content, and phytolith concentration were higher in the mature leaves. Tissue-cultured seedlings had a significantly higher moisture content than grafted seedlings. Ash and silicon demonstrated the same order of grafted seedlings > tissue-cultured seedlings > seed-cultured seedlings. The highest phytolith concentration was found in tissue-cultured seedlings. The phytolith morphotypes in D. brandisii seedling leaves raised by different methods were identical and grouped into eight morphotypes. The phytolith assemblage was characterized by a high frequency of bilobate and saddle, accounting for more than 60%, whereas the morphotypes of elongate, blocky, flabellate, and circular phytoliths accounted for the smallest proportion, normally all below 4.5%. The phytolith size demonstrated an increasing trend in the maturing leaves. The sizes of bilobate, saddle, and acute phytoliths expanded the fastest in tissue-cultured seedling leaves, implying rapid growth of the cell in tissue-cultured seedlings. Accordingly, the tissue-cultured seedlings contained more silicon and phytoliths of larger sizes, which could be a better choice of stock supply for establishing large-scale plantations. If the stock of the seed-cultured and grafted seedlings is to be used, silicon fertilizer application is an optimal option to boost seedling growth.
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Tyree, E. Loeta. "Phytolith analysis of olive oil and wine sediments for possible identification in archaeology". Canadian Journal of Botany 72, n. 4 (1 aprile 1994): 499–504. http://dx.doi.org/10.1139/b94-067.
Testo completoAbstract (sommario):
Phytoliths are microscopic, amorphous silica or crystalline, inclusions of plant origin that can be of diagnostic value in an archaeological context. This study demonstrated that distinct phytoliths can be extracted from two major extant and ancient crop species: olive (Olea europaea L.) and grape (Vitis vinifera L.). Nonacid digestion of leaves and fruits of two Greek olive cultivars (Megareitiki and Kothreiki) and a Greek grape cultivar (Agiorgitiko) showed that olive and grape contained distinctly different calcium phytoliths and that olive fruit flesh and stone contained sclereids. Olive oil sediment from traditionally produced oil from Greece and Turkey and barrel sediment from traditional Greek red wine were found to contain phytoliths and (or) sclereids corresponding to their fruit of origin. Olive oil could therefore be distinguished from wine, making the nonacid phytolith extraction method a potentially useful alternative to chemical analysis of ancient storage jar residues. Key words: calcium and silica phytoliths, olive, grape, sediment analysis.
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Lisztes-Szabó, Zsuzsa, Szilvia Kovács, Péter Balogh, Lajos Daróczi, Károly Penksza e Ákos Pető. "Quantifiable differences between phytolith assemblages detected at species level: analysis of the leaves of nine Poa species (Poaceae)". Acta Societatis Botanicorum Poloniae 84, n. 3 (2015): 369–83. http://dx.doi.org/10.5586/asbp.2015.027.
Testo completoAbstract (sommario):
<p>The taxonomic value of phytolith assemblages and their degree of variability within different species of the same genus is still an undervalued issue in the botanical range of phytolith studies. However the understanding of grass phytolith variance and its implications to plant systematics is doubtless.</p><p>In the present study phytoliths of the lateral shoots (leaves) of nine, globally distributed <em>Poa</em> species (Pooideae – Poaceae) are described. Phytoliths were recovered from <em>Poa</em> specimens by the dry ashing technique. Altogether 6223 disarticulated phytoliths were counted (approximately 500–700 phytoliths per species) in 54 plant samples, which cover six shoots of nine species. Not only the relative frequency of each morphotype was calculated, but measurements were conducted to determine the biogenic silica content of <em>Poa</em> lateral shoots. A phytolith reference collection for the nine selected species of a worldwide importance was also compiled. The description of the most significant phytolith morphotypes and their taxonomic relationships are given here.</p><p>Results suggest that the biogenic silica content of the <em>Poa</em> lateral shoots was determined to be relatively high within all nine species. Phytolith assemblage data was subjected to multivariate statistical analyses (e.g., CA and PCA) in order to find differences and similarities among the nine <em>Poa</em> species. Results show that the two closely related <em>Poa</em> of the <em>P. pratensis</em> species group, namely the <em>P. pratensis</em> and <em>P. angustifolia</em>, only slightly differ from the other <em>Poa</em> species if we consider their rondel-trapeziform short cells (SC) phytolith frequencies.</p>
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Speranskaya, Natalia Y., Tatyana A. Zhembrovskaya e Daria G. Bobkova. "Comparative analysis of phytolith spectra of steppe and forest phytocoenoses ". Acta Biologica Sibirica 7 (15 dicembre 2021): 505–13. http://dx.doi.org/10.3897/abs.7.e78448.
Testo completoAbstract (sommario):
The primary research goal is to identify differences and diagnostic features of the phytolith spectra of the steppe and forest phytocoenoses. The paper presents the research results of recent soils from various communities. The authors employ the phytolith analysis method. The isolation of phytoliths from recent soils has been carried out with the help of the maceration method and from plants – the dry ashing method. The authors counted the phytoliths using the Olympus BX-51 light microscope. Additionally, the authors have compiled the spectra using the 2C software. The paper compares the phytolith spectra of plain and mountain steppe phytocoenoses. The comparison reveals that the considered plain communities are more similar in phytolith composition than the mountain ones. The following morphotypes are common for all spectra: low conical rondel particles and psilate ribbed particles. These are the forms that characterize steppe communities. Analysis of phytolith spectra of the mountain forest communities demonstrates that the presence of ribbed particles of psilate is common for all spectra. The common feature of all forest spectra is the presence of psilate symmetrical particles, polylobate trapeziforms, lanceolates (trichomes) with a massive base, and trapeziform bilobate (“Stipa-type”) particles. In the spectra of all pine forests, there is a low content or complete absence of needle phytoliths. Diagnostic features of individual phytocoenoses have not been found. The most significant is the ratio of individual phytolith forms in the phytolith spectrum. The comparative analysis of phytolith spectra of the phytocoenoses in the south of western Siberia is carried out for the first time.
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Mercader, Julio, Freya Runge, Luc Vrydaghs, Hughes Doutrelepont, Corneille E. N. Ewango e Jordi Juan-Tresseras. "Phytoliths from Archaeological Sites in the Tropical Forest of Ituri, Democratic Republic of Congo". Quaternary Research 54, n. 1 (luglio 2000): 102–12. http://dx.doi.org/10.1006/qres.2000.2150.
Testo completoAbstract (sommario):
Phytoliths record late Quaternary vegetation at three archaeological sites in the Ituri rain forest. The oldest deposits, dated to ca. 19,000 to 10,000 14C yr B.P., contain abundant phytoliths of grasses but also enough arboreal forms to show that the landscape was forested. The late-glacial forests may have had a more open canopy than today's. Younger phytolith assemblages show that the northeast Congo basin was densely forested throughout the Holocene. Archaeological materials among the phytoliths show that people lived in this region during the Pleistocene. Therefore, Pleistocene and Holocene prehistoric foragers probably inhabited tropical forests of the northeast Congo basin many millennia before farming appeared in the region.
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Li, Nannan, Dorothy Sack, Guizai Gao, Lidan Liu, Dehui Li, Xiuyun Yang, Dongmei Jie, Hongyan Liu, Jichen Shi e Chengcheng Leng. "Holocene Artemisia-Chenopodiaceae-dominated grassland in North China: Real or imaginary?" Holocene 28, n. 5 (7 dicembre 2017): 834–41. http://dx.doi.org/10.1177/0959683617744268.
Testo completoAbstract (sommario):
The Songnen grasslands were traditionally thought to be dominated by Artemisia and Chenopodiaceae plants as early as the late Pleistocene. However, increasing evidence has called that interpretation into question. To shed new light on the paleovegetation evolution of the arid and semi-arid steppe in North China, phytolith assemblages preserved in the region’s sand-paleosol sequence (section Daike) are used as a proxy for paleovegetation structure. Results show that both the sand and paleosol layers in the Songnen grassland sections contain well-preserved phytoliths attributed to different families of grass. This is the first direct evidence of the nature of the vegetation that existed during the sandy layer episodes. Moreover, the phytolith evidence represented in the samples indicates that plant successions happened within the subfamilies of Poaceae through the time. Referring to phytoliths in modern plants and topsoils, and using statistical analyses, we propose that phytolith assemblages in the section Daike originated from Poaceae-dominant communities rather than an Artemisia-Chenopodiaceae ecosystem. The phytoliths, and evidence from the historical and modern pollen-vegetation relationships, lead to rejection of the hypothesis of a past widespread Artemisia-Chenopodiaceae ecosystem in the Songnen grasslands. Using published radiocarbon and thermoluminescence data, it is proposed that the present Poaceae-dominated grasslands developed as early as the early Holocene. This study also highlights the usefulness of phytolith analysis in paleovegetation reconstruction in arid and semi-arid lands.
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Thorn, Vanessa C. "New Zealand sub-Antarctic phytoliths and their potential for past vegetation reconstruction". Antarctic Science 20, n. 1 (26 ottobre 2007): 21–32. http://dx.doi.org/10.1017/s0954102007000727.
Testo completoAbstract (sommario):
AbstractPhytoliths in the modern vegetation of sub-Antarctic Campbell Island are compared with those in the soil beneath to assess the accuracy of vegetation reconstructions made from dispersed phytolith assemblages. The soil phytoliths alone suggest the source vegetation is a grassland association for all study sites, which reflects none of the herb, fern or shrub component of the overlying vegetation. It is concluded that at this locality dispersed phytoliths on their own are not reliable indicators of source vegetation and should be used with caution in this context for palaeoecological studies. However, they can provide useful botanical information where all other organic material is absent. With further research, based on the abundance and diversity of Poaceae phytoliths observed in this and other studies, dispersed phytoliths from the fossil record have the potential to contribute significantly to the understanding of grassland ecosystem development in the geological past.
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Speranskaya, N. Yu, M. Yu Solomonova, M. M. Silantyeva, Yu V. Genrih e M. S. Blinnikov. "Фитолиты злаков Северного Алтая". Ukrainian Journal of Ecology 8, n. 1 (10 marzo 2018): 762–71. http://dx.doi.org/10.15421/2018_278.
Testo completoAbstract (sommario):
<p>The article presents the results of analysis of the phytolith composition of cereals in the Northern Altai. Some 23 species of <em>Poaceae</em> have been studied. For each species, we analyzed a set of silicon particles in leaves, stems, and generative structures. We selected from 22 to 27 significant morphotypes of phytoliths, depending on their morphological affinity. Our results were compared with the wetting factor. We also analyzed the ratio of the composition of phytoliths of cereals and their ecological (edaphotopic) groups and life forms. We founded the correlations between several morphotypes of cereal phytoliths and life forms with optimum species moistening.</p>
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Solomonova, M. Yu, e S. D. Kotov. "Variability in size and shape of polylobed leaf phytoliths in three populations of Dactylis glomerata L." Проблемы ботаники Южной Сибири и Монголии 21, n. 2 (17 novembre 2022): 183–86. http://dx.doi.org/10.14258/pbssm.2022080.
Testo completoAbstract (sommario):
The article presents the results of morphometric study of polylobed trapeziform phytoliths of the leaf epidermis of Dactylis glomerata. The relevance of the study lies in the difficulty of establishing the limit of phytolith variability when using morphometry for paleoecological purposes. The studies were performed according to the recommendations of the International Committee for Phytolith Morphometry using the ImageJ software and its PhytolithsBatch plugin. For the first time, the characteristics of the parameters of the size and shape of polylobed trapeziform phytoliths are given. Previously, the study of these particles was not carried out due to their absence in cultivated cereals. The variability of the studied particles within populations and between representatives of individual populations is considered. The length of the phytolith and related indicators are subject to the greatest variability, the width and inscribed radius are the most stable.
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Okunaka, Ryota, Tatsuichiro Kawano e Jun Inoue. "Holocene history of intentional fires and grassland development on the Soni Plateau, Central Japan, reconstructed from phytolith and macroscopic charcoal records within cumulative soils, combined with paleoenvironmental data from mire sediments". Holocene 22, n. 7 (22 dicembre 2011): 793–800. http://dx.doi.org/10.1177/0959683611430409.
Testo completoAbstract (sommario):
Phytolith and macroscopic charcoal in cumulative soils on the Soni Plateau, Central Japan, were evaluated to clarify the Holocene history of intentional fires and grassland development, and to compare the findings with those derived from pollen and charcoal records in sediments taken from a nearby mire in the previous study. Prior to ~1500 cal. BP, Bambusoid short-cell phytoliths and Pleioblastus-type and Bambusoideae-type bulliform cell phytoliths were abundant with scarce charcoal particles (<1000 particles/cm3). In contrast, since ~1500 cal. BP Andropogoneae-type bulliform cell phytoliths and Bilobate short-cell phytoliths were dominant with abundant charcoal particles (>1000 particles/cm3). Based on correlating these records with pollen and charcoal records in mire sediments, prior to ~1500 cal. BP, dwarf bamboo flourished on the forest floor under largely fire-free conditions, whereas since ~1500 cal. BP, grassland dominated by Japanese pampas grass has been sustained by periodic intentional burning that has continued until the present day.
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Alexandre, Anne, Amarelle Landais, Christine Vallet-Coulomb, Clément Piel, Sébastien Devidal, Sandrine Pauchet, Corinne Sonzogni et al. "The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations". Biogeosciences 15, n. 10 (31 maggio 2018): 3223–41. http://dx.doi.org/10.5194/bg-15-3223-2018.
Testo completoAbstract (sommario):
Abstract. Continental atmospheric relative humidity (RH) is a key climate parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor, which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility of making model–data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) – 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH from 80 to 40 % decreases the 17O-excess of phytoliths by 4.1 per meg/% as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg/%. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the plant may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.
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Buffington, Abigail Francesca, Andrew Weiland, Julia Arnold e Drew Arbogast. "What is Your “Phytolith Load”? An Examination of the Potential for Cross-Contamination During Phytolith Extraction". Ethnobiology Letters 9, n. 2 (25 aprile 2018): 65–74. http://dx.doi.org/10.14237/ebl.9.2.2018.955.
Testo completoAbstract (sommario):
Phytoliths—amorphous opal silica bodies that form in living plant tissues—are assumed to be stable components of a soil matrix, minimally impacted by normal physical forces. This stability enables archaeologists to access an archive of prior vegetative landscapes when discrete horizons are recovered. However, there is a small chance of phytoliths moving in a laboratory setting via aeolian forces, especially after they have been isolated from other materials such as clay, organics, and carbonates, and when multiple samples are being processed simultaneously. As a result, an assessment of contamination risk on sample extraction is necessary for interpreting the results of phytolith analyses. We designed a study to test the potential for contamination on slides in two different locations of the phytolith laboratory. The results of our study inform how we can improve on phytolith processing protocols and analyses to reduce the potential effect of cross-contamination between samples.
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de Melo Farnezi, Múcio Mágno, Enilson de Barros Silva, Lauana Lopes dos Santos, Alexandre Christofaro Silva, Paulo Henrique Grazziotti, Jeissica Taline Prochnow, Israel Marinho Pereira e Ivan da Costa Ilhéu Fontan. "Potential of Grasses in Phytolith Production in Soils Contaminated with Cadmium". Plants 9, n. 1 (15 gennaio 2020): 109. http://dx.doi.org/10.3390/plants9010109.
Testo completoAbstract (sommario):
Cadmium (Cd) is a very toxic heavy metal occurring in places with anthropogenic activities, making it one of the most important environmental pollutants. Phytoremediation plants are used for recovery of metal-contaminated soils by their ability to absorb and tolerate high concentrations of heavy metals. This paper aims to evaluate the potential of grasses in phytolith production in soils contaminated with Cd. The experiments, separated by soil types (Typic Quartzipsamment, Xanthic Hapludox and Rhodic Hapludox), were conducted in a completely randomized design with a distribution of treatments in a 3 × 4 factorial scheme with three replications. The factors were three grasses (Urochloa decumbens, Urochloa brizantha and Megathyrsus maximus) and four concentrations of Cd applied in soils (0, 2, 4 and 12 mg kg−1). Grass growth decreased and increased Cd concentration in shoots of grasses with the increased Cd rates in soils. The toxic effect of Cd resulted in production and Cd occlusion in phytoliths produced in shoots of the grasses. Grasses showed potential for phytolith production, independent of soil type, providing phytoextraction of Cd in phytoliths. Megathyrsus maximus was the grass with the highest tolerance to Cd, evidenced by higher production and Cd capture in phytoliths for the evaluated soils. Phytolith production by grasses in Cd-contaminated soils is related to genetic and physiological differences of the evaluated grasses and Cd availability in soils.
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Alexandre, A., J. Crespin, F. Sylvestre, C. Sonzogni e D. W. Hilbert. "The oxygen isotopic composition of phytolith assemblages from tropical rainforest soil tops (Queensland, Australia): validation of a new paleoenvironmental tool". Climate of the Past 8, n. 1 (22 febbraio 2012): 307–24. http://dx.doi.org/10.5194/cp-8-307-2012.
Testo completoAbstract (sommario):
Abstract. Phytoliths are micrometric particles of amorphous silica that form inside or between the cells of higher plant tissues throughout the life of a plant. With plant decay, phytoliths are either incorporated into soils or exported to sediments via regional watersheds. Phytolith morphological assemblages are increasingly used as proxy of grassland diversity and tree cover density in inter-tropical areas. Here, we investigate whether, along altitudinal gradients in northeast Queensland (Australia), changes in the δ18O signature of soil top phytolith assemblages reflect changes in mean annual temperature (MAT) and in the oxygen isotopic composition of precipitation (δ18Oprecipitation), as predicted by equilibrium temperature coefficients previously published for silica. Oxygen isotopic analyses were performed on 16 phytolith samples, after controlled isotopic exchange (CIE), using the IR Laser-Heating Fluorination Technique. Long-term mean annual precipitation (MAP) and MAT values at the sampled sites were calculated by the ANUCLIM software. δ18Oprecipitation estimates were calculated using the Bowen and Wilkinson (2002) model, slightly modified. An empirical temperature-dependant relationship was obtained: δ18Owood phytolith-precipitation (‰ vs. VSMOW) = −0.4 (±0.2) t (°C) + 46 (±3) (R2 = 0.4, p < 0.05; n = 12). Despite the various unknowns introduced when estimating δ18Oprecipitation values and the large uncertainties on δ18Owood phytolith values, the temperature coefficient (−0.4 ± 0.2‰ °C−1) is in the range of values previously obtained for natural quartz, fresh and sedimentary diatoms and harvested grass phytoliths (from −0.2 to −0.5‰ °C−1). The consistency supports the reliability of δ18Owood phytolith signatures for recording relative changes in mean annual δ18Osoil water values (which are assumed to be equivalent to the weighted annual δ18O precipitation values in rainforests environments) and MAT, provided these changes were several ‰ and/or several °C in magnitude.
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Meunier, Jean-Dominique, Anne Alexandre, Fabrice Colin e Jean-Jacques Braun. "Interet de l'etude du cycle biogeochimique du silicium pour interpreter la dynamique des sols tropicaux". Bulletin de la Société Géologique de France 172, n. 5 (1 settembre 2001): 533–38. http://dx.doi.org/10.2113/172.5.533.
Testo completoAbstract (sommario):
Abstract Recent studies on the biogeochemical cycle of silica put new constraints into models of genesis and evolution of silica in tropical environments. The role of plants in weathering mass balances are illustrated by phytolith studies. In Dimonika (Congo) latosols, dissolved silica originates mainly from the dissolution of phytoliths rather than from the dissolution of non-biogenic silicates. In andosols from La Reunion island (Indian Ocean), a 15 cm thick, biogenic silica accumulation formed within 4000 years from bamboo forests fires. The turn-over of silica by plants must therefore be taken into account in studies of weathering rates. Weathering rates of trachytic ash layers in La Reunion island show that all the primary minerals are destroyed and that 50% of amorphous secondary Al/Si products are transformed into halloysite. Theses rates, which are faster than the ones obtained in the Hawaii islands, may strongly influence the turn-over of carbon in soils. Besides, phytoliths preserved from dissolution may help to decipher the records of environmental changes in soils. In Salitre (Brazil), the phytolith distribution has been calibrated with charcoal and pollens. The age of phytoliths, which increases with depth, allow to trace the savanna/forest changes.
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Mulholland, Susan C., George Rapp Jr., Amy L. Ollendorf e Ronald Regal. "Variation in phytolith assemblages within a population of corn (cv. Mandan Yellow Flour)". Canadian Journal of Botany 68, n. 8 (1 agosto 1990): 1638–45. http://dx.doi.org/10.1139/b90-210.
Testo completoAbstract (sommario):
This project investigates the effects of leaf side, leaf position, individual plant, and hill (or plant group) on phytolith assemblages from Zea mays L. cultivar Mandan Yellow Flour. Thirty-two samples were examined, and 200 phytoliths were classified from each sample. Statistical analysis indicates that leaf side is significant at the 0.05 level above random counting variation; leaf position, individual plant, and hill are not generally significant beyond the effect of leaf side. Analysis of a single sample, either a half or entire leaf, is not sufficient for compilation of representative phytolith assemblages from a plant population. Phytolith reference collections should not be based on single samples of each species. Multiple samples from a population need to be analyzed to obtain information on assemblage variation within the population. The variation of corn phytolith assemblages in this study overlaps those of many Panicoid grasses, indicating that additional morphological characters need to be identified to distinguish corn from wild grasses in the Great Plains. Key words: phytoliths, corn, frequencies, variation.
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Wen, Mengdan, Rencheng Li, Richard S. Vachula, Xiude Wang, Yang Qin, Qiang Yuan e Xinyue Tao. "The ratio of microcharcoal to phytolith content in soils as a new proxy of fire activity". Holocene 30, n. 11 (14 luglio 2020): 1567–78. http://dx.doi.org/10.1177/0959683620941086.
Testo completoAbstract (sommario):
Microcharcoal in soils and sediments is an ideal proxy for studying fire activity. Phytoliths in soils and sediments record the environmental conditions in which the phytoliths were formed by plants. However, our understanding of the relationships between fire activity, plant communities, and the preservation of microcharcoal and phytoliths in soils and sediments remains limited. In this study, we collected soils and sediments across a gradient of burned and unburned forest in southwest China, and analyzed the microcharcoals and phytoliths in these samples to understand the relationships between these microfossils (ratios of microcharcoal to phytolith particles (Ch/Ph)), fire activity, and vegetation cover. We show that the Ch/Ph ratios recorded fire activity and were significantly different across the gradient of burned to unburned forest. The highest and lowest ratios (0.25 and 0.01) were found in burned forest (Bs1) and unburned forest samples (Us2), respectively. The ratios gradually decreased with increasing distance from the fire. This study suggests the ratio (Ch/Ph) to be a useful proxy for studying fire activity and/or history using soils and sediments.
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Hart, DM. "The Plant Opal Content in the Vegetation and Sediment of a Swamp at Oxford Falls, New South Wales, Australia". Australian Journal of Botany 36, n. 2 (1988): 159. http://dx.doi.org/10.1071/bt9880159.
Testo completoAbstract (sommario):
Opal phytoliths in the leaves of 10 native species growing in and around a swamp were isolated and quantified, and shape and surface detail examined with a scanning electron microscope (SEM). The amount of plant opal in the leaves ranged from 0.10 to 2.45% by dry weight, and phytolith forms most commonly found were spheres, rods and sheets. Phytoliths in the silt size range of the swamp sediment were isolated by a simple fractionation technique. It was found that the forms with a small surface area to volume ratio survived in the sediment.
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Farnezi, Múcio Magno de Melo, Enilson de Barros Silva, Lauana Lopes dos Santos, Alexandre Christofaro Silva, Paulo Henrique Grazziotti, Luís Reynaldo Ferracciú Alleoni, Wesley Costa Silva et al. "Potential of Forage Grasses in Phytoremediation of Lead through Production of Phytoliths in Contaminated Soils". Land 12, n. 1 (26 dicembre 2022): 62. http://dx.doi.org/10.3390/land12010062.
Testo completoAbstract (sommario):
Phytoremediation has become a promising technique for cleaning Pb-contaminated soils. Grasses have a phytoextractor potential for extracting metal from soil by transporting it and accumulating it in high concentrations in their shoots, and they have the ability to immobilize and inactivate it via phytoliths. The objective of this work was to evaluate the phytoremediation potential of forage grasses through the production of phytoliths and the occlusion of Pb in the phytoliths cultivated in Pb-contaminated soils. Three greenhouse experiments were conducted in a completely randomized design, separated by soil type (Typical Hapludox, Xanthic Hapludox and Rhodic Hapludox), in a 3 × 4 factorial scheme consisting of three forage grasses (Megathyrsus maximus, Urochloa brizantha and Urochloa decumbens) and four Pb rates (0, 45, 90 and 270 mg kg−1) with four repetitions. The forage grasses were influenced by increases in the Pb concentrations in the soils. The higher Pb availability in Typic Quartzipsamment promoted Pb toxicity, as indicated by the reduced dry weights of the shoots, increased phytolith production in the shoots, increased Pb in the shoots and Pb occlusion in the phytoliths of the forage grasses. The production and Pb capture in the phytoliths in the grasses in the Pb-contaminated soils were related to the genetic and physiological differences in the forage grasses and the Pb availability in the soils. Urochloa brizantha was the most tolerant forage to the excess Pb, with a higher production of phytoliths and higher Pb occlusion in the phytoliths, making it a forage grass that can be used in the future for the phytoremediation of Pb-contaminated soils.