Did temperate trees survive the Last Glacial Maximum in the North Sea Basin? A critical review of current evidence

The hypothesis that temperate tree taxa survived the Last Glacial Maximum (LGM; 26.5–19 ka cal BP) in cryptic northern refugia has significant implications for European biogeography and postglacial vegetation history. Recently, sedimentary ancient DNA recovered from offshore sediment cores in the Southern River System of the North Sea Basin has been interpreted as evidence for the local persistence of temperate woodland taxa during the LGM. This review critically evaluates that hypothesis by synthesising the currently available palaeobotanical and sedimentary ancient DNA evidence from the North Sea Basin and adjacent terrestrial regions. Independent palaeoclimate reconstructions consistently indicate cold, dry conditions, continuous permafrost and temperatures well below the ecological requirements of temperate woodland trees. These reconstructions are broadly congruent with pollen, plant macrofossil, vertebrate and coleopteran records, which collectively indicate the persistence of low‐productivity arctic to subarctic steppe–tundra vegetation throughout the region during the LGM. This strong convergence among independent palaeoenvironmental datasets contrasts with limited support for the local persistence of temperate woodland communities throughout the LGM in the North Sea Basin.