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Reading the pages of a tree’s biography


GenTree’s multi-scale tree sampling project resulted in more than 15,000 wood cores from trees sampled all over Europe: 3 cores from 25 trees of 12 species across 200 sites. These cores all ended up at the laboratories of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), where the tree rings revealed in the cores are measured and analysed.

“The trees have archived what they were doing in the past,” said Patrick Fonti, team leader in the tree-ring research group at WSL. “By looking at the tree rings you can fly back in time and reconstruct the interaction of the tree with the environment.”

Cores are carefully graded for quality. Those that are less than perfect can still be used to study the anatomy of the wood. The very best, those that are unbroken and that reach the pith (the heart of the tree trunk) are selected for dendrochronology — the study of dated tree rings.

We recognise the familiar tree-ring-pattern in the cut surface of a tree trunk or branch because the wood laid down in early summer, when growth is at its fastest, is usually lighter in colour. The width of the ring laid down each year can reveal much about the climate and other external factors that affect the growth of the tree.