Decadal-scale pollen records link land use and plant diversity change across European lowlands over seven millennia.

Understanding the long-term drivers of biodiversity change requires datasets that expand the timescale of ecological observations. Using lake sediments as natural archives, we reconstruct plant diversity change at high temporal resolution across the Swiss Plateau, a key region for European land use history. Contiguous pollen records, from three sites, spanning 7.6 millennia, were constrained by 227 radiocarbon dates and partly annually laminated sequences, yielding decadal-scale chronologies. We examine relationships between palynological richness (PRI), a proxy for plant diversity, and reconstructed land use probability (LUP) across six cultural-historic epochs. Vegetation histories are similar across sites: while beech forests persist throughout, other deciduous trees decline and grassland taxa expand from the Neolithic onwards. Plant diversity responds strongly to land use, increasing with openings, cultivation and fire, and declining during crises such as the Migration Period and the Black Death. Medieval and early modern landscapes support the highest richness, while diversity has declined in recent decades, likely due to industrialised agriculture. Our findings show that humans have been major drivers of plant diversity change in European lowlands for more than seven millennia and that sustainable land use legacies from the past may hold the key to reversing today's biodiversity losses.