Subfossil yew (Taxus baccata) wood from eastern England reveals mid-Holocene climate and environmental changes

Placing current climate trends and extremes in the long-term context of pre-industrial variability requires annually resolved absolutely dated proxy archives.

Here, we benefit from hundreds of exceptionally well-preserved subfossil yew (Taxus baccata) trees that were excavated over decades from near sea-level peat-rich sediments in the Fenland region of eastern England. We combined dendrochronological and radiocarbon dating to develop a millennium-long tree-ring width (TRW) chronology for the mid-Holocene. We further measured stable oxygen and carbon isotopes (δ¹⁸O and δ¹³C) in a subset of samples, which allowed absolute dating of the yew chronology between 5225 and 4148 calendar years BP. An eco-physiological model was then developed to reconstruct hydroclimate changes on interannual to centennial timescales.

Our findings suggest that relatively dry soil and atmospheric conditions favoured yew growth, while higher groundwater tables and wetter soils reduced TRW. These relationships are contrary to those we observed in living yew trees today, likely due to hydrological rather than climatic changes in space and time. Our new hydroclimate reconstruction reveals unusually wet conditions around 4,200 years ago, when extensive yew woodlands suddenly disappeared from eastern England. We propose that the extinction of Fenland taxus was likely driven by a sea-level rise in the North Sea, a prolonged negative phase of the North Atlantic Oscillation, and significant riverine flooding. These hydroclimate and biogeographic transformations provide new insights into the causes and consequences of the hotly debated 4.2 ka event in the North Atlantic/European sector.