New research suggests that there could have been some ice free pockets in Ice Age Scandinavia, generally believed to have been as completely covered in ice as Greenland is today, and that pine and spruce varieties may have survived in them for tens of thousands of years.
Laura Paducci et al., Glacial Survival of Boreal Trees in Northern Scandinavia. Science 2012. Pay per view.
It seems that some modern Scandinavian trees do not have direct southern ancestors but also that there are sedimentary layers with their pollen belonging to the Ice Age. This challenges the generally accepted paradigm that imagined Scandinavia fully covered in snow-ice for much of the last Ice Age.
For example, the excellent online resource Don's Maps, shows the following ice cover for the Last Glacial Maximum, c. 20,000 years ago:
|Based on Svendsen 2004|
|Author: Väino Poikalainen, horizontal stripes are lakes|
It seems now that this idea was wrong after all, not just pockets of forest are known to have existed in Central Europe in the LGM but also now it is claimed that even inside Scandinavia itself some forested areas survived all the time:
Two locations in Norway have proved particularly lucrative for the researchers. One of them, Andøya Island, in north-western Norway, is the source of material dated between 17,700 and 22,000 years-old. During the last ice age, the island was an ice-free pocket, one "refuges" on the edge of the enormous ice sheet, which blanketed at that time nearly all of Scandinavia.
"The other evidence, which supports the surviving conifers in the midst of an ice age, originates in Trøndelag, central Norway. One hypothesis is that trees were able to survive on the top of nunataks, the exposed ridges or peaks of mountains protruding from glacial cover, or in more sheltered areas close to the coast where proximity to the temperate conditions of the Atlantic Ocean favoured survival.
Source: Science Daily.