Lacustrine environmental archives with annually laminated (varved) sediments permit a calendar-year chronology and allow calculation of precise sediment accumulation rates. We present multiproxy analyses of a varved sediment record from Holzmaar (West-Eifel Volcanic Field, Germany) for the last 16,000 years providing a continuous diatom stratigraphy supported by physical and chemical parameters with a centennial resolution. Patterns of diatom assemblages infer the trophic history of Holzmaar. There is a distinct variation at the Pleistocene/Lateglacial transition characterized by a replacement of Staurosira construens with Stephanodiscus minutulus, increases of Ca/Ti, TOC/TN ratios and biogenic silica, together suggesting an increase in lacustrine productivity and a shift of the lake's trophic status from oligotrophic to mesotrophic. These conditions remain during the Bölling/Alleröd interstadial. During the Younger Dryas stadial, there is a decrease on organic productivity as reflected by TOC, a subtle increase on benthic and epiphytic diatoms, indicating colder and dry conditions, and S. minutulus remains dominant suggesting increased winds. The Postglacial is dominated by Lindavia radiosa, S. minutulus and Nitzschia paleacea. The latter occurs between 9000-6000 cal yr BP together with an increase of TOC/TN and TS suggesting eutrophication with periodic anoxia during the Holocene Thermal Maximum. After 2200 cal yr BP, L. radiosa and Pantocsekiella comensis are dominant suggesting warmer conditions (especially during the Medieval Climate Anomaly) and thermal stability. Increased surface runoff is reflected in higher values of Ti and MS, suggesting more humidity and enhanced by anthropogenic disturbance. Moreover, the appearance of Aulacoseira subarctica is related to a cold and wet period coinciding with the Little Ice Age. In addition to environmental changes, our multiproxy analyses track human impact since the Middle Neolithic.
This dataset provides the raw pollen counts for the late-glacial sediment sequence retrieved from Lake Haemelsee (Germany) in 2013. The counts are presented against both depth (cm core depth) and time (cal. yr BP) and cover the time interval from ca 15.200 to 10.400 cal yr BP. A total of 106 samples were counted, with higher sampling resolution around the onset and end of the Younger Dryas, and lower sampling resolution elsewhere in the core. The pollen record provides information about both regional vegetation change as well as changes in the within-lake flora. It was produced to inform on the exact age and duration of major palynological transitions during the late-glacial Cores were retrieved from the lake using a 3-m long UWITEC piston corer deployed from a floating coring platform during field work in July 2013. Volumetric samples were obtained from splits of the core and processed in the laboratory (University of Amsterdam, the Netherlands) using standard protocols.