Exploring the potential for a 9000-year tree-ring chronology consisting of subfossil oak material from southern Scandinavia

Abstract

In this study, we present the initial results from a long-term initiative to develop a multi-millennial tree-ring width (TRW) chronology for subfossil oak (Quercus spp.) trees in South Scandinavia. We have constructed 40 TRW chronologies, primarily from oak trunks extracted from peatlands, archaeological sites, drainage ditches, and infrastructure projects, as well as some submerged material. The trees included in these chronologies have been dendrochronologically dated and/or dated by radiocarbon, showing a temporal spread from 6911 ± 246 BCE to 1117 CE. Significant assemblages of trees are found during the periods 6000–4500 BCE, 3500–2600 BCE, 1750–1200 BCE, 900–400 BCE, and 200 BCE–500 CE, with intervening periods exhibiting low sample replication or gaps. The paleoclimatic information extracted from TRW and replication data may vary based on the substrate in which the trees were rooted, geographical locations, and the prevailing climate conditions during their growth. Nevertheless, extending the oak TRW chronologies is crucial because (1) no such long and annually resolved climate records from southern Scandinavia exist, (2) there is a widespread lack of detailed paleoclimatic proxies spanning multi-millennial periods, and (3) it will provide an essential dating tool for wooden archaeological artifacts. This study is the first in a series aimed at refining paleoclimatic and ecological reconstructions in southern Scandinavia. It demonstrates the potential to develop South Scandinavian TRW chronologies covering the last 9000 years, filling a geographical gap in an ecologically sensitive region.