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Ginkgo plants and the search for Pliocene-CO2 levels

The reconstruction of ancient environments is one of the major goals of palaeontology. One of the most important factors in shaping the environment is the atmospheric concentration of carbon dioxide (CO2). A commonly used praxis to assess Deep Time CO2-concentrations is via a dependent proxy. The aim of this study was to estimate concentrations in the late Pliocene using the ratio between stomata and epidermis cells (Stomatal Index, SI) on the surface of Ginkgo adiantoides leaves as a proxy. In order to establish a reliable reference for the quantitative relationship between CO2 concentration and this SI, measurements ideally should be done with specimen grown across a wide range of known CO2 concentrations. Additionally the reference taxon has to be as closely related to the fossil taxon as possible since the SI at a given CO2 concentration and its reaction to changing concentrations varies greatly between different species. Due to these constraints the baseline for the present analysis was calculated using Ginkgo biloba, the closest living relative to the now extinct Ginkgo adiantoides. For this purpose leaves were taken from herbarium archives collected across the last 150 years, as well as leaves freshly collected in 2023 and 2024, together with abundant data from the literature. In order to visualize the epidermal cells and stomata a number of microscopic techniques were used. Utilizing this modern calibration dataset CO2 concentrations were estimated based on Ginkgo leaves from the Late Pliocene floras of Frankfurt am Main and Ruppach-Goldhausen (both Germany).

Details

Author
Patrick Guldan1, Dieter Uhl2
Institutionen
1Senckenberg Forschungsinstitut und Naturmuseum, Germany;Goethe Universität Frankfurt am Main, Germany; 2Senckenberg Forschungsinstitut und Naturmuseum, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/3320-p580