33 research outputs found
Modern vegetation proxies reflect Palaeogene and Neogene vegetation evolution and climate change in Europe, Turkey, and Armenia
Latitudinal variation in morphological traits of the genus Pinus and its relation to environmental and phylogenetic signals
Leaf physiognomy as environmental indicator : An analysis of extant and fossil floras
Dokument 1.pdf: Hauptteil
Dokument 2.html: Hinweis auf den in dieser Arbeit erstellten Kalibrationsdatensatz in der Datenbank PANGAEA
Dokument 1.zip: ZIP-Paket mit in dieser Dissertation verwendetem Datenmaterial
Blattphysiognomische Merkmale in der Vegetation, wie z. B. die BlattgröĂe, Blattform und Blattrand, werden von den jeweiligen Umweltbedingungen eines Standortes entscheidend beeinfluĂt. Die Vegetation kann ĂŒber diese Beziehung von Umwelt und Blattphysiognomie auch umgekehrt als Indikator fĂŒr UmweltverhĂ€ltnisse dienen.
Diese Studie untersucht den Zusammenhang von blattphysiognomischen Merkmalen und verschiedenen Umweltparametern in der europĂ€ischen Vegetation anhand von Laubgehölzen. HierfĂŒr wurde ein Kalibrations-Rasterdatensatz erstellt, der floristische und Umweltdaten vereinigt. Die blattphysiognomischen Daten basieren auf synthetischen Florenlisten; die Umweltdaten umfassen klimatologische und vegetationsökologische Daten. Aufgrund der hohen Rasterdatendichte lassen sich Verteilungsmuster dieser Parameter fĂŒr den europĂ€ischen Raum darstellen und die ZusammenhĂ€nge analysieren.
Die Untersuchung der ZusammenhĂ€nge von Umweltparametern und physiognomischen Blattmerkmalen in der Vegetation zeigt eine hohe Korrelation von temperaturbezogenen Umweltparametern, wie z. B. der mittleren Jahrestemperatur oder der Anzahl der Frosttage mit der AusprĂ€gung einiger Blattparameter wie z.B. der Laminabasis und dem Blattrandtyp. Dagegen lassen Niederschlagsparameter, wie z. B. der mittlere Jahresniederschlag, keine deutliche Korrelation mit der blattphysiognomischen Zusammensetzung der Vegetation erkennen. Die Identifizierung dieser ZusammenhĂ€nge werden genutzt, um anhand von Transferfunktionen AbschĂ€tzungen fĂŒr verschiedene Umweltparameter aus der blattphysiognomischen Zusammensetzung der rezenten Vegetation zu erhalten.
Ferner wurde der Datensatz anhand einer Cluster-Analyse in bezug auf die blattphysiognomische Zusammensetzung untersucht, wobei charakteristische âblattphysiognomische Vergesellschaftungenâ aufgedeckt wurden, die zur Klassifikation verschiedener Vegetationstypen herangezogen werden können. Innerhalb dieser âblattphysiognomischen Klassenâ zeigt sich eine deutlich Zunahme der blattphysiognomischen DiversitĂ€t mit zunehmender VariabilitĂ€t der Umweltparameter. So sind ânördlicheâ Vegetationstypen durch eine relativ homogene blattphysiognomische Zusammensetzung gekennzeichnet, wĂ€hrend âsĂŒdlicheâ (mediterrane) Vegetationstypen eine erheblich gröĂere blattphysiognomische DiversitĂ€t erkennen lassen.
SchlieĂlich wurden die an der rezenten Vegetation erstellten Transferfunktionen zur AbschĂ€tzung von PalĂ€oumweltverhĂ€ltnissen anhand von drei fossilen Blattfloren aus dem europĂ€ischen TertiĂ€r benutzt. Hierbei kamen verschiedene Rekonstruktionsmethoden zur Anwendung, wobei ein direktes lineares Ordinationsverfahren zu den realistischsten Ergebnissen fĂŒhrt, da diese AbschĂ€tzungen mit alternativen Rekonstruktionsmethoden, wie z.B. der Koexistenz-Methode, hohe Ăbereinstimmungen aufweisen.Dokument 1.pdf: Main part
Dokument 2.html: Linking information to database PANGAEA with calibration dataset
Dokument 1.zip: Zipped package with data material used in this thesis
Physiognomic traits of plant leaves such as size, shape or margin are decisively affected by the prevailing environmental conditions of the plant habitat. On the other hand, if a relationship between environment and leaf physiognomy can be shown to exist, vegetation represents a proxy for environmental conditions.
This study investigates the relationship between physiognomic traits of leaves from European hardwood vegetation and environmental parameters in order to create a calibration dataset based on high resolution grid cell data. The leaf data are obtained from synthetic chorologic floras, the environmental data comprise climatic and ecologic data. The high resolution of the data allows for a detailed analysis of the spatial dependencies between the investigated parameters.
The comparison of environmental parameters and leaf physiognomic characters reveals a clear correlation between temperature related parameters (e.g. mean annual temperature or ground frost frequency) and the expression of leaf characters (e.g. the type of leaf margin or the base of the lamina). Precipitation related parameters (e.g. mean annual precipitation), however, show no correlation with the leaf physiognomic composition of the vegetation. On the basis of these results, transfer functions for several environmental parameters are calculated from the leaf physiognomic composition of the extant vegetation.
In a next step, a cluster analysis is applied to the dataset in order to identify âleaf physiognomic communitiesâ. Several of these are distinguished, characterised and subsequently used for vegetation classification. Concerning the leaf physiognomic diversity there are precise differences between each of these "leaf physiognomic classes". There is a clear increase of leaf physiognomic diversity with increasing variability of the environmental parameters: Northern vegetation types are characterised by a more or less homogeneous leaf physiognomic composition whereas southern vegetation types like the Mediterranean vegetation show a considerable higher leaf physiognomic diversity.
Finally, the transfer functions are used to estimate palaeo-environmental parameters of three fossil European leaf assemblages from Late Oligocene and Middle Miocene. The results are compared with results obtained from other palaeo-environmental reconstructing methods. The estimates based on a direct linear ordination seem to be the most realistic ones, as they are highly consistent with the Coexistence Approach
Taxon-specific variability of leaf traits in three long-ranging fossil-species of the Paleogene and Neogene: Responses to climate?
European Leaf Physiognomic Approach ELPA
Physiognomic traits of plant leaves such as size, shape or margin are decisively affected by the prevailing environmental conditions of the plant habitat. On the other hand, if a relationship between environment and leaf physiognomy can be shown to exist, vegetation represents a proxy for environmental conditions.
This study investigates the relationship between physiognomic traits of leaves from European hardwood vegetation and environmental parameters in order to create a calibration dataset based on high resolution grid cell data. The leaf data are obtained from synthetic chorologic floras, the environmental data comprise climatic and ecologic data. The high resolution of the data allows for a detailed analysis of the spatial dependencies between the investigated parameters. The comparison of environmental parameters and leaf physiognomic characters reveals a clear correlation between temperature related parameters (e.g. mean annual temperature or ground frost frequency) and the expression of leaf characters (e.g. the type of leaf margin or the base of the lamina). Precipitation related parameters (e.g. mean annual precipitation), however, show no correlation with the leaf physiognomic composition of the vegetation. On the basis of these results, transfer functions for several environmental parameters are calculated from the leaf physiognomic composition of the extant vegetation.
In a next step, a cluster analysis is applied to the dataset in order to identify âleaf physiognomic communitiesâ. Several of these are distinguished, characterised and subsequently used for vegetation classification. Concerning the leaf physiognomic diversity there are precise differences between each of these "leaf physiognomic classes". There is a clear increase of leaf physiognomic diversity with increasing variability of the environmental parameters: Northern vegetation types are characterised by a more or less homogeneous leaf physiognomic composition whereas southern vegetation types like the Mediterranean vegetation show a considerable higher leaf physiognomic diversity.
Finally, the transfer functions are used to estimate palaeo-environmental parameters of three fossil European leaf assemblages from Late Oligocene and Middle Miocene. The results are compared with results obtained from other palaeo-environmental reconstructing methods. The estimates based on a direct linear ordination seem to be the most realistic ones, as they are highly consistent with the Coexistence Approach