Present forest biodiversity patterns in France related to former Roman agriculture

Combined archaeological and ecological investigations in large ancient forests in France have revealed dense networks of ancient human settlements dating from the Roman period. We demonstrate a strong correlation between present-day forest plant diversity patterns and the location of Roman farm buildings. Plant species richness strongly increases towards the center of the settlements and the frequency of neutrophilous and nitrogen-demanding species is higher. This pattern is paralleled by an increase in soil pH, available P and ?15N, indicating the long-term impact of former agricultural practices on forest biogeochemical cycles. Ancient Roman agricultural systems are increasingly being identified in contemporary French forests; the broad extent and long-lasting effects of previous cultivation shown in this study require that land-use history be considered as a primary control over biodiversity variations in many forest landscapes, even after millenia of abandonment.