Postglacial development

We will now turn to the changes in more recent times. As an example we take the development of terrestrial ecosystems in south Sweden. But first some notes on driving forces – changes in climate with glaciations. During the geologic development of the Earth there have been a number of glaciations, with interglacial periods in between (Figure 11.4). The last glaciation extended from approximately 100 000 years ago to 10 000 years ago, with a maximum 20 000 years ago. During this period, massive ice fields covered large parts of the continents. At its maximum extent, the Weichselian Ice Sheet covered eastern Denmark, Finland, Norway, Sweden and the Baltic states, as well as northern Germany, northern Poland and western Russia. The Laurentide Ice Sheet covered Canada and the northern United States, and the Patagonian Ice Sheet southern Chile and Argentina. The ice started to leave south Sweden 17 000 years ago and the whole country was free from inland ice approximately 7000 years ago.

Information on the development of terrestrial ecosystems since the last glaciation is obtained from analyses of lake sediments and peat with their contents of pollen, fruits and other plant remains. The conditions and development of ecosystems after the last glaciation in south Sweden, as well as elsewhere, attract great interest. We have chosen to follow two main sources: Birks (1986) and Berglund et al. (2007). The first gives a review of late-quaternary biotic changes in terrestrial and lake environments, in particular north-west Europe. The second summarises changes in vegetation over 17 000 years in the southernmost province of Sweden, Scania (Skåne).