Rowin VAN LANEN
(Netherlands Centre for Dendrochronology, The Netherlands)

Abstract: The Post-Roman Lowlands are characterized by severe river flooding, population decrease, and major land-use changes. In this dynamic region economic and demographic revival set in as early as the seventh century (Merovingian Period), with rivers regaining much of their transport-geographical importance and (new) trade relations intensifying. From this point on the Netherlands shifted from the periphery of the Roman Empire to the centre of North-Sea trade (Carolingian Period). This study focuses on reconstructing Early Medieval (supra)regional trade relations in the Lowlands in order to understand the nature of this revival by using Dorestad as a focus point.
Using a new international data infrastructure and repository for dendrochronology, the DCCD (http://dendro.dans.knaw.nl), it is for the first time possible to analyze combined archaeological and palaeo-ecological tree-ring data sets from the Netherlands and abroad in terms of, among others, tree species, chronological age, germination and dying-off phases, provenance, and (with archaeological artifacts) wood technology.
The dataset we used consists of tree-ring series from barrels (re-used as water wells), planks, shipwrecks, and poles from Dorestad (397 series) and a total of 1587 series representing 102 archaeological sites in other parts of the Low Countries. Our results indicate that Dorestad was part of a trade network along the North Sea coast that included agricultural settlements with strong ties to the German Rhineland. A second timber group consisted of oak from the levees along the river Rhine suggests a second local trade network near the towns of Utrecht, Katwijk and Leiderdorp. The results improve our understanding on the adaptation of trade networks to river dynamics and dendrochronological provenance studies.

Keywords: Multi-disciplinary approach, data integration, dendrochronology, archaeology, Early Middle ages