Potential and significance of leaf trait changes of long lived species during the Paleogene

Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval

Potential and significance of leaf trait changes of long lived species during the Paleogene

Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval

Potential and significance of leaf trait changes of long lived species during the Paleogene

Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval

An exafs and volumetric study of the formation of hydrides on Pd particles encaged in Y-zeolite

EXAFS performed on 10 Å particles of Pd in the network of a Y-zeolite has shown that in vacuum the structure of the metal is similar to that of the bulk.The lattice expansion observed on the EXAFS data when 500 mbar H2 is introduced, is slightly smaller than what is observed on the bulk upon the formation of the β-hydride.It is inferred that on small clusters, where the number of sites is reduced, the stoichiometry of the hydride is reduced to 0.4 H/Pd instead of 0.6

Preparation and characterization of palladium – chromium catalysts generated from mixed salts

Palladium chromate and dichromate have been synthetized and characterized by X-ray diffraction and EXAFS. These compounds were reduced between 200 and 600° C in flowing hydrogen. Below 400° C, 20 A Pd particles supported on amorphous chromium oxide are observed. Above this temperature, EXAFS shows that a bimetallic compound is formed corresponding to the composition Pd88Cr12

Étude du frittage de l’oxyde de nickel par analyse de fourier des profils de diffraction et diffusion centrale des rayons X

L’étude du frittage de l’oxyde de nickel feuilleté par analyse de Fourier des profils de diffraction et diffusion centrale des rayons X permet de mettre en évidence deux mécanismes de frittage suivant le domaine de température. A 230 °C, l’oxyde de nickel est constitué de feuillets d’épaisseur comprise entre 20 et 30 Å correspondant au diamètre le plus fréquent des cristallites. Les feuillets dont les grandes dimensions sont de l’ordre de 1 000 à 2 000 Å sont constitués d’un grand nombre de cristallites tels qu’un plan (111) est parallèle au plan des feuillets. Jusqu’à 400 °C, le grossissement des cristallites a lieu parallèlement au plan des feuillets. Au-dessus de 400 °C, la soudure des feuillets entraîne le grossissement des cristallites perpendiculairement au plan des feuillets initiaux

Role of chromium in the stability of Ni/Al2O3 catalysts for natural gas reforming

Ni/Al2 O3 and Ni–Cr/Al2O3 catalysts prepared with melt salts of Ni and Al (Al/Ni=0.5) were studied by magnetic measurements, electron microscopy and catalytic properties. An increase in the catalytic activity and stability during partial oxidation of methane and CO reforming reactions at 973 K was produced by the chromium addition. The Ni–Cr alloy was 2 formed by reduction at high temperature 1073 K , producing a dilution effect of Ni crystal and modifying the basicity of the support. Both effects would inhibit the catalyst deactivation increasing the useful life and stability of the nickel.Fil: Gónzalez, María Gloria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Nichio, Nora Nancy. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Moraweck, B.. Institut de Recherches sur la Catalyse; FranciaFil: Martin, G.. Institut de Recherches sur la Catalyse; Franci

EDGE AND EXAFS STUDY OF CHARCOAL SUPPORTED Pt-Fe CATALYSTS

Les catalyseurs bimétalliques Pt-Fe/charbon ont une activité et une sélectivité remarquables en hydrogénation sélective de l'aldéhyde cinnamique en alcool cinnamique. L'EXAFS montre que la composition correspondant au maximum d'activité est une solution solide homogène de fer dans le platine. Les modifications des formes des seuils observées pour les deux métaux traduisent des réarrangements électroniques probablement responsables de l'activité catalytique.Pt-Fe charcoal supported catalysts are very active and selective for the partial hydrogenation of cinnamic aldehyde into ethylenic alcohol. EXAFS shows that the solid exhibiting a strong maximum of activity is an homogeneous f.c.c. solution of Fe in Pt. The marked variations of edge shapes of the two metals observed in the alloys account for the modification of electronic structure and hence, of the catalytic properties