Sturdy Scandinavian conifers survived the ice age

A Murdoch University researcher has helped rewrite history after radiocarbon dating and genetic analysis proved that Scandinavian conifers in the high arctic survived the last ice age for several thousands of years.

Dr James Haile from Murdoch’s ancient DNA laboratory said that until now it was presumed that the Scandinavian landscape was devoid of trees during the ice age.

“The history of conifers, spruce and pine in Scandinavian forests needs to be rewritten,” Dr Haile said.

“We’ve now disproved previously held beliefs that the forests were the products of species migration from areas of southern and eastern Europe that were ice free during the last ice age.”

The research, which was published in the journal Science, was led by Professor Eske Willerslev and Dr Tina Jørgensen from the Centre for GeoGenetics, University of Copenhagen, Laura Parducci from the Universities of Uppsala and Inger Greve Alsos from Tromsø University Museum.

“Our results demonstrate that not all the Scandinavian conifer trees share the same recent ancestors, as we once believed,” Professor Willerslev said.

“There were groups of spruce and pine that survived the harsh climate in small ice-free pockets, or in refuges, as we call them, for tens of thousands of years, and then were able to spread once the ice retreated.

“Other spruce and pine trees have their origins in the southern and eastern ice-free areas of Europe.

“Therefore, one can now refer to ‘original’ and later naturally ‘introduced’ Scandinavian conifer species.”

The results have emerged, in part, by Dr Haile studying the DNA of modern spruce, which clearly portray two Scandinavian types - and also by analysing the composition of pine and spruce DNA in sediments from lake-core samples. Additionally, the researchers analysed other ancient DNA from fossil pollen to reach their conclusions.

The research took place in Norway on Andøya Island and Trøndelag. It appears that Andøya Island was an ice-free region, a ‘refuge’ on the edge of an enormous ice sheet blanketing most of Scandinavia. In Trøndelag there are two theories of refuges - the trees may have survived at the top of mountain peaks not covered in ice or in sheltered areas close to the coast of the Atlantic Ocean.

“The existence of ice age refuges for spruce and pine in the arctic, which we have demonstrated, will force a re-evaluation of species recolonisation rates; and where the trees survived, probably so too did other components of the ecosystem,” Dr Haile said.

The study challenges conventional scientific notions of the spreading of trees, biodiversity and survival in harsh environments from a global perspective - especially with regards to climate change or other changes and interventions in nature.