Jennie Sandström has been doing research for several years.

In her laboratory are tree samples from 200 trees that come from one of her completed projects. It was about looking for traces of historic fires in the future nature reserve Horten, on the border between Västernorrland and Jämtland counties, via the annual rings of the trees.

The data was then used as a basis for forest management plans in the area. The trees are not harmed by the sampling, emphasizes Jennie. Sometimes an injury can act as a vaccination.

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One of the trees that Jennie Sandström examined in the project in Horten still puzzles her. See the tree sample and hear why the mystery seems to remain unsolved. Photo: Anna Beijron/SVT