Oak, elm and hazel forests thrived on Doggerland, the now-submerged landmass between Britain and mainland Europe, more than 16,000 years ago — thousands of years before any pollen record from the British and European uplands had registered temperate forest cover. That is according to a sedimentary ancient DNA study published in Proceedings of the National Academy of Sciences, led by Professor Robin Allaby of the University of Warwick.
Professor Allaby’s team analysed sedaDNA from 252 sediment samples collected from 41 marine cores along the Southern River, a prehistoric watercourse selected for its well-preserved sediments. The researchers traced the region’s ecological history from approximately 16,000 years ago through to its final submergence beneath the southern North Sea.
Wood Central understands that the work was funded by the European Research Council under the Horizon 2020 LOST FRONTIERS project, and that the discovery represents the largest sedimentary ancient DNA reconstruction of the submerged landscape conducted to date. Sedimentary DNA accumulates in fine alluvial sediments but degrades through repeated reworking, the inverse of pollen, which preserves well in peat bogs and persists across sediment turnover.
The Warwick team paired the genetic record with sedimentological analysis of every core, separating samples derived from a local source from those carrying material reworked or transported from elsewhere. Within the secure cores, oak, elm and hazel were identified in deposits laid down before the Allerød, the warm interstadial roughly 13,900 years ago that marks the close of the last glaciation.
Lime, a warmth-loving species, appeared around 2,000 years before its earliest known existence on the British mainland. This suggests parts of southern Doggerland functioned as a northern refuge whilst the surrounding European uplands remained too cold for broadleaf trees.
“We unexpectedly found trees thousands of years earlier than anyone expected,” Professor Allaby said. The team also recovered evidence the North Sea fully formed later than previously documented, undercutting decades of pollen-based reconstructions that had placed widespread temperate forest cover in the region towards the end of the last glaciation, not well before it.
The team also detected DNA from Pterocarya, a walnut relative thought to have vanished from northwestern Europe in the Hoxnian interglacial around 400,000 years ago. The signal was recovered from two secure cores, ELF19 and ELF45, with DNA degradation patterns at 30 per cent, indistinguishable from oak, hazel, willow, alder and elm in the same Late Pleniglacial layers.
On that basis, the Warwick team concluded the Pterocarya signal represents a relic population that survived in northwestern Europe well into the last glaciation rather than reworked ancient material. This pushes the regional extinction date for the genus forward by hundreds of thousands of years.
The persistence of these temperate species across the last glaciation supports the theory of microrefugia, small climatically-buffered pockets that allowed cold-sensitive trees to survive in higher latitudes than the surrounding climate would otherwise support. The presence of such refugia is the leading explanation for Reid’s Paradox, the long-standing puzzle in palaeobotany over how European forests recolonised cleared ground at rates far faster than seed and pollen dispersal can account for.
The findings add to a growing body of archaeological evidence reshaping understanding of European forest heritage, as Wood Central has reported in coverage of heritage forest protection debates across Europe and Australia. Co-author Professor Vincent Gaffney of the University of Bradford said the findings overturn the long-held view of Doggerland as a mere transit corridor between Britain and continental Europe.
“Doggerland was not only a heartland of early human settlement,” Professor Gaffney said, describing the landmass as a fulcrum for how prehistoric communities resettled northern Europe across millennia. The sedaDNA record also traces the gradual flooding of the landscape, with seagrass appearing in the upper core layers as marine waters advanced.
The team identified woodland habitats capable of supporting wild boar and other game species, resources critical to early Mesolithic communities long before the Maglemosian culture emerged on the British mainland around 10,300 years ago. The PNAS paper draws on 252 sediment samples across 41 marine cores along the prehistoric Southern River, with parts of southern Doggerland remaining above sea level until approximately 7,000 years ago — 1,150 years after the Storegga Slide tsunami struck the North Sea, Professor Allaby said.
For more information: R.G. Allaby, R. Ware, R. Cribdon, T.A. Hansford, T. Kinnaird, D. Hamilton, L. Kistler, P. Murgatroyd, R. Bates, S. Fitch & V. Gaffney, Early colonization before inundation consistent with northern glacial refugia in Southern Doggerland revealed by sedimentary ancient DNA, Proc. Natl. Acad. Sci. U.S.A. 123 (11) e2508402123, https://doi.org/10.1073/pnas.2508402123 (2026).
