European Palaeobotany and Palynology Conference 2026

Atmospheric CO2 and drought are key parameters of climate change. Both have profound impact on plant performance and therewith on both the carbon and hydrological cycle. Analysis of stable carbon isotope ratios in plant tissues is a common methods to determine ecophysiological responses as this data can provide information about a plant’s photosynthetic activity throughout its life.

Here, we investigate plant response and interaction of ancient lineages including lycophytes, sphenopsids and cordiatales, which have evolved under vastly different climatic conditions and persisted through several shifts major shifts in global climate. To test adaptation, we analyze δ13C values of well-preserved upper Carboniferous plant fossils from the Saar-Nahe basin (Germany). Here multiple sites with contrasting habitat ecologies are available that allow to elaborate on the potential wet/dry tolerance of individual plant taxa. For the sphenopsids, we moreover provide selected supplementary data from the Mesozoic and Cenozoic as well as historical herbarium specimen and modern representatives of Equisetum. Results of fossil and (sub-)modern δ13C values are compared to further evaluate the effects of increasing drought in combination with changing atmospheric CO2 on the general performance and photosynthetic potential of ancient plant lineages, with a focus on horsetails.