Increased Holocene Diversity in Europe Linked to Human-Associated Vegetation Change

Aim: It is widely reported that aspects of present-day global biodiversity are declining, with humans largely to blame. However— perhaps paradoxically—in Europe, floristic diversity and human populations have grown in tandem for millennia. Disturbance intensity and habitat heterogeneity potentially explain this phenomenon, though we lack understanding of how human land use intensity affected biodiversity at numerous spatial scales over the Holocene. Here, we examine the relationships between anthropogenic vegetation change and floristic diversity over the last 12 millennia in Europe, at multiple spatial scales. Location: Europe. Time Period: The Holocene (11,700–100 cal yr BP). Major Taxa Studied: Plants. Methods: We examined the spatio-temporal dynamics of, and relationships between, floristic richness, evenness and compositional turnover with an index of anthropogenic vegetation change since 11,700 cal yr. BP, analysing 7853 pollen samples from 213 records (sites). We evaluated how changes to the proportional site occupancies of human-associated and other taxa related to diversity patterns. Results: (1) Floristic richness, evenness, and compositional turnover increased from 9000 years ago to 1850CE. (2) Temporal increases in richness and evenness were positively associated with the anthropogenic vegetation index in the majority of vegetation zones and sites, whereas compositional turnover was only associated with the anthropogenic index at the site level. (3) Holocene site occupancies of all human-associated taxa were positively associated with biodiversity gains, whereas the results for other taxa (that were not associated with people) were mixed. Main Conclusions: Following the onset of warmer Holocene conditions, floristic diversity initially declined, while subsequent increases were positively associated with human impacts over the vast majority of Europe. From the mid-Holocene onwards, farming populations increasingly disturbed European landscapes—perhaps replicating the now-lost megafaunal disturbance regimes—to produce patchy and increasingly diverse vegetative communities, the legacies of which are still present today