Water-borne macroscopic plant particle transport through central and northern Europe during warming phases: a hypothetical spreading mechanism for climatic pioneers

Abstract

This paper presents a new hypothesis on spreading and immigration of pioneer plants. It is speculated that during phases of sudden climate warming, seeds and other parts of plants were transported by rivers from central Europe into the North Sea and the Baltic areas and drifted on to surrounding shores. Some parts have remained in the records as macrofossils, while in other cases the plants are proposed to have continued their life cycle in the new areas. The principle is illustrated by examples from different areas and times: Weichselian Lateglacial finds in NW Germany suggest that tree trunks were brought northward. For central and northern Sweden exceptionally strong glacio-isostatic rebound could have followed pronounced land surface depression after the ice-sheet meltings. This would have transformed coasts to land quickly, promoting the growth of seeds and plants in areas that are now far inland. If this hypothesis is valid it can explain the presence of anomalously early, warm vegetations in newly deglaciated areas. The rapidity of water-borne immigration following a climatic warming can also open up for a possibility of quick immigration to other former near-coast areas and river banks in Europe. Based on an example of a warmth requiring palaeovegetation at Vr⊘gum in Denmark and the fact that trees survived in central Europe during the coldest part of the Weichselian it is suggested that short-lived, palaeobotanically hitherto unknown warm phases might be worth looking for in the terrestric records.

Key Words:

• Pioneer plants
• water-borne transport
• climate warming
• glacio-isostacy
• Schleswig
• Denmark
• Sweden
• European rivers
• Baltic area
• Weichselian
• Eemian