The trees survived the ice age, staying in place

The last ice age costly for Europe. At its peak — 20-25 thousand years ago — glaciers up to 3 km thick covers about 6,000,000 km ². Hard to believe that vegetation could survive this onslaught, and most scientists believe that Scandinavia was devoid of trees, until thawed for about 9 thousand years ago.

However, the analysis of ancient DNA has shown that some conifers (pine, spruce) felt fine in Norway and 20 thousand years ago. The data indicate that the trees migrate more slowly than assumed when faced with climate change. And this may have important implications for models that predict the horrors of the current global warming.

Researchers extent of ancient vegetation typically rely on fossil pollen from lake sediments. But some scholars argue that this method does not give the full picture, because trees do not always produce pollen when they are on the border of its range, and are close to extinction.

For example, in 2002, a physical geographer Leif Cullman University of Umea (Sweden) conducted radiocarbon dating of fossilized pieces of stems, roots and cones of spruce, pine and birch trees found in the Scandinavian mountains. It turned out that there were trees 14 thousand years ago, when everything was covered in ice. But other researchers argue that a colleague had to deal with the contaminated samples.

In order to solve the problem, a group led by Eske Villersleva University of Copenhagen (Denmark) analyzed pollen from lake sediments Trøndelag region, located in central Norway, and from the island Annaeus the north. In Trendalage found mitochondrial DNA ate the age of 10 300 years. Also found on the island of chloroplast DNA of spruce and pine, which is about 17 700 and 22 000 years, respectively. Researchers reject the possibility of contamination, because lake sediments usually neutralized organic compounds.

The authors conclude that the trees are likely to persist in small ice-free areas of Western Scandinavia. They do not have to migrate to the south in order to survive.

Contemporary models suggest that after warming coniferous forests returned to the north very quickly, but it can also be wrong. According to new data, they did not need to come back — they did not go anywhere.

The study is published in the journal Science.

Prepared according to ScienceNOW.

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