Warfare dendrochronology: Trees witness the deployment of the German battleship Tirpitz in Norway

Claudia Hartl, Scott St. George, Oliver Konter, Lorenz Harr, Denis Scholz, Andreas Kirchhefer, Jan Esper

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


War has an immediate and obvious effect on people and communities, but its impacts on local ecology can be more subtle. This paper shows how one military encounter in the Second World War has left a clear legacy in the northern forests of Norway, trackable more than seventy years later. We used annual growth rings of ∼180 pine and ∼30 birch trees as witnesses of the deployment of the German battleship Tirpitz at the Kåfjord. The Tirpitz was the target of several Allied air attacks, but the Kriegsmarine (German navy from 1935 to 1945) used artificial smoke, consisting of chlorosulfonic acid and zinc/hexachloroethane, to hide the ship. These smoke-screen actions throughout 1944 caused pine forests surrounding the Kåfjord to exhibit a strong and unusual growth decline during the following year. Severe defoliation and limited photosynthetic activity likely triggered this decline. The tree damage extended up to 4 km away from the Tirpitz. In the most extreme case, growth was interrupted for nine years. ‘Warfare dendrochronology’ could help to evaluate potential environmental impacts of the Second World War on forest health and composition elsewhere in the European theatre.

Original languageEnglish (US)
Article number100212
StatePublished - Sep 2019

Bibliographical note

Funding Information:
We thank Markus Kochbeck, Philip Bergforth, Ben Lehmann, Bianca Müller, Johannes Neumann and Marcus Schwarz for help with laboratory work and several geography students from the Johannes Gutenberg University Mainz who supported fieldwork during the North Scandinavia Excursions in summer 2016 and 2017. We also thank the forest owner Finnmarkseiendom for sampling permission as well as historian Arvid Petterson, Lakselv, for proving the first lead towards Tirpitz and artificial smoke in Kåfjord. This work was supported by the German Science Foundation [SCHO 1274/13-1, Inst 247/665-1 FUGG, ES 161/9-1, HA 8048/1-1] and the Alexander von Humboldt Foundation .

Publisher Copyright:
© 2019 Elsevier Ltd


  • Anthropogenic impact
  • Forest disturbance
  • Pollution
  • Second World War
  • Smoke screen
  • Tree ring


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