Black Death land abandonment drove European diversity losses

The current prevailing perception is that human impacts on the biological realm have been overwhelmingly negative. Here, we test this narrative by considering the consequences for aspects of floristic diversity of the ‘Black Death era’ (1300–1400 ce), where one third of Europe's population died within half a decade. Based on evidence from 109 pollen records spanning the Common Era, we find increasing floristic diversity from 0 to ~1300 ce as human populations increased, followed by rapid and substantial diversity reductions during the famine- and disease-driven human mortality events of the ‘Black Death era’. As human populations recovered following the mortality shock, diversity also recovered. Strikingly, it was landscapes characterized by cereal cultivation that generated both the overall Common Era increases and the Black Death era declines in diversity. The highest diversity levels were achieved in human-generated, mosaic landscapes, highlighting the integral role of human action in biodiverse European landscapes.