During the past ca. 2.7 millions of years long periods of cold climate were interrupted by rapid switches to temperate conditions comparable to those of the current interglacial, the Holocene. Climate changes in Europe were drastic (ca. + 10°C during the interglacials if compared to the glacials) and extremely rapid (reaching +5° C in ca. 100 years). Drastic and rapid climatic changes released expansion and contractions of species and communities across the continent. The long-term consequence of strong climatic variability were extinctions and thus biodiversity reductions, specifically in European forests.
In this Swiss National Science Foundation project we study the vegetation composition of several interglacials, spanning from marine isotope stage (MIS) 5 to 12. Of particular interest is MIS 5e, the Eemian interglacial, because climatic conditions ca. 130000 years ago were slightly warmer than during the Holocene average (ca. +2°C). Here novel pollen, stomata, spore and charcoal records will be gained from Spiezberg, an Interglacial site in the Bernese Oberland. Multivariate analyses will allow numeric biostratigraphical comparisons with other interglacial profiles from the Bernese Region (e.g. Meikirch, Beerenmösli at Gondiswil) that possess radiometric or thermoluminescence dates to gain a reliable biostratigraphic age attribution of the Spiezberg interglacial. In addition, physical dating methods will be explored.
This will allow positioning the Spiezberg biostratigraphy into the Swiss and European interglacial context (e.g. by comparison with Mondsee or Monticchio). This procedure will be repeated at another Swiss or Central European site to gain new insights about vegetation and ecosystem responses to climate warming before the advent of modern Homo sapiens, an information which may be applied to restore future natural vegetation and ecosystems, e.g. in national parks.
Patrick Schläfli, Erika Gobet, Willy Tinner