The historical dynamics of calcareous grasslands in the central and southern Franconian Jurassic mountains: a comparative pedoanthracological and pollen analytical study

Abstract

We present a thematic set on pedoanthracological research. In this paper a comparative analysis of soil wood charcoal from calcareous grasslands and pollen from an alluvial sediment profile has been carried out to reconstruct the history of calcareous grassland habitats in the Franconian Jura. Seven tree and shrub species (groups) were recorded from soil charcoal. Charcoal from Pinus dominated all spectra, indicating open forests or even less intensively grazed grasslands, which is supported by findings of remains of Juniperus and Ligustrum. Charcoals from Fagus, Quercus and Abies, indicating more closed forests, were comparatively rare. AMS radiocarbon datings assigned the charcoals to the period of the Roman Empire, the late Middle Ages and the early Modern Times correlating with the peaks of microcharcoals in the sediment profile. Juniperus pollen was used as indicator of calcareous grasslands. Plantago lanceolata, Galium type, Apiaceae, Ranunculaceae and Ballota/Galeopsis pollen-types were significantly correlated with the occurrence of Juniperus and identified as further indicators. Pinus was selected as an indicator for open forests. Pollen of all indicator species occurred throughout the pollen profile starting in the Iron Age. The main peak of grassland indicator species pollen types was in the high Middle Ages. Maxima of Pinus pollen have been recorded in the periods of the Roman Empire and the late Middle Ages. We suggest extension maxima of less intensively grazed calcareous grasslands during the Roman Empire period and during the late Middle Ages and of intensively grazed grasslands in the high Middle Ages in the latter case correlated to intensive mining activities north of the study region. Increase in Pinus and the conversion of open into woody grasslands in the late Middle Ages/beginning of Modern Times was triggered by the abandonment of arable farming due to the decline of human population caused by pest diseases.