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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

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

Moraweck, Karolin 25 September 2017 (has links) (PDF)
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.
2

Bestimmungs- und Verbreitungsatlas der Tertiärflora Sachsens – Angiospermenblätter und Ginkgo

Eberlein, Mareike 08 July 2015 (has links) (PDF)
Die vorliegende Dissertation stellt den ersten Teil eines Nachschlagewerks zur Tertiärflora Sachsens dar. Dieser Teil umfasst alle Taxa, die sich auf Angiospermenblätter und auf Ginkgo gründen. Auf einen Überblick zum regionalgeologischen Kenntnisstand des Tertiärs in Sachsen folgend, werden phytostratigrafische Konzepte vorgestellt und ein historischer Abriss der tertiärpaläobotanischen Forschung in Sachsen gegeben. Nach einer Erfassung aller bis Ende 2013 für das sächsische Tertiär publizierten pflanzlichen Makrofossilien und deren Fundorte (Primärdaten), welche durch projektbezogene Qualifikationsarbeiten Dritter durch zusätzliche Attribute ergänzt und vereinheitlicht wurden, werden die fossilen Taxa von Angiospermenblättern selektiert, deren Daten harmonisiert, ausgewertet und auf einen einheitlichen Forschungsstand gebracht. Für 187 von 235 untersuchten Taxa werden Datenblätter für einen Bestimmungsatlas erstellt. In diesem Atlas werden makro- und mikromorphologische Merkmale der Arten beschrieben, sowie Angaben zur Systematik, Synonymie, Paläoökologie und räumlicher und zeitlicher Verbreitung gemacht. Der beschreibende Teil wird durch Abbildungen und instruktive Zeichnungen ergänzt. Im Ergebnisteil werden die Daten nach ihrer Qualität innerhalb der Literatur begutachtet und anwendungsbezogen diskutiert. Eine Bibliografie der umfangreichen paläobotanischen Literatur für sächsische Pflanzenfossilien rundet die Arbeit ab. Um die taxon- und fundortbezogenen Daten visualisieren und effektiv verwalten zu können, werden diese in ein Open Source-Geoinformationssystem (GIS) überführt. Die im GIS implementierten Untersuchungsergebnisse ermöglichen erstmalig sowohl eine Generierung von Verbreitungs-karten für die Taxa tertiärer Angiospermenblätter und des Ginkgos in Sachsen als auch eine Abfrage von topografischen, geologischen und paläobotanischen Informationen zu den Fossilfundstellen. Ein für das Fossilmaterial entwickelter Bestimmungsschlüssel erlaubt zudem eine grobe Determination der Funde im Gelände. Das Kompendium wird in gedruckter und digitaler Version für die freie Nutzung zur Verfügung gestellt. / The thesis represents the first part of a reference book to the Tertiary flora of Saxony. All taxa based on leaves of angiosperms and on Ginkgo are included in this compendium. After an overview about the geological state of knowledge on the Tertiary in Saxony, phytostratigraphic concepts are introduced and a historical survey on the Tertiary paleobotanical research in Saxony is given. All plant macrofossils published from Saxonian Tertiary until end of 2013 and their sites of discovery (primary data) were recorded. This data were supplemented by additional attributes and unified through project-based M.Sc. theses. Subsequently, taxa of fossil leaves were selected, their data evaluated and brought to a consistent state of research. Data sheets for 187 out of 235 examined taxa were established for a determination atlas. Macro- and micromorphological attributes are described in this atlas and information are given about the systematic, synonymy, palaeoecology and spatial and temporal distribution. The describing part is illustrated by images and instructive drawings. The documented data were surveyed and discussed related to their quality within the literature in the result part. A bibliography of the extensive palaeobotanical literature for plant fossils of Saxony completes the work. The taxon and locality related data are implemented into an open source geographical information system (GIS) in order to visualize and to manage them effectively. For the first time, the results of this thesis implemented in the GIS allow the generation of distribution maps for the taxa of leaves of Tertiary angiospermes and Ginkgo in Saxony. Furthermore it enables to query topographical, geological and paleobotanical information about the fossil sites. A determination key was developed for the fossil material that allows a rough determination of the findings in the field. The compendium will be available for free use in a printed as well as in a digital version.

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