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Detecting the palaeoenvironmental potential of Arctic driftwood

WSL tree-ring research: driftwood
Sampling driftwood at the east coast of Greenland (Traill)
 
Driftwood sampling sites
Distribution of boreal conifer species: Pinus sp. (divided in Pinus sp. in North America and Pinus sylvestris/Pinus sibirica in Eurasia), Larix sp., Picea sp., and Abies sp., together with driftwood sampling sites in Greenland, Iceland, Svalbard and on the Faroe Islands and the large pan-arctic river systems. Source: Hellmann et al. 2013.
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Arctic driftwood is an exceptional proxy at the interface of marine and terrestrial environments. Large pan-arctic river systems deliver boreal wood to the Arctic Ocean, where it is included in the sea ice and transported for several years over thousands of kilometres. Finally deposited on shallow Arctic coastlines of Greenland, Iceland or Svalbard, for instance, it not only provides information on ocean current dynamics and ice-rift, but also on source-region characteristics.

Within our project at WSL we aim to reveal the palaeoenvironmental potential of Arctic driftwood by applying dendrochronological methods. Our compilation of 2’500 driftwood samples was collected on Greenland, Iceland, Svalbard and the Faroe Islands. The species composition within the driftwood reflects the boreal forest species distribution. Scots pine is the most frequent species among the driftwood and mostly logged. Boreal reference chronologies are used to crossdate and hence determine the provenance region of the wood.

Tree-ring measurements of the Scots pine samples show that ~80% of the stems originate in the Angara region, the main tributary to the Yenisei River. The spatial and temporal distribution of the samples can be explained by river discharge, logging and associated drift-floating activities, distance to the Arctic sea ice, as well as the direction of ocean currents. Analyses of more samples and other species, ideally covering a wide time span, are nevertheless essential for further conclusions on ocean current patterns, sea-ice dynamics, postglacial uplift rates, and boreal forest activities.

At the eastern Siberian Lena River, samples were collected from living, dead and subfossil trees, as well as from driftwood along the river, to develop ring-width chronologies, which will ideally span the past millennia. Absolutely dated and annually resolved records will help to improve references for driftwood dating and to better understand dynamic processes within the delta.

Publication

Hellmann L, Tegel W, Eggertsson O, Schweingruber FH, Blanchette R, Gärtner H, Kirdyanov A, Büntgen U (2013) Tracing the origin of Arctic driftwood. Journal of Geophysical Research – B 118: 68-76  doi:10.1002/jgrg.20022

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