IRREVERSIBLE IMPACT OF PAST LAND USE ON FOREST SOILS AND BIODIVERSITY

TLDR

Forest expansion in western Europe has largely occurred on former agricultural land, and plant diversity differs between recent forests and ancient ones that were already forested around 1800, with some areas having been deforested during Roman times. The study examined how long the effects of past agriculture persist in forest ecosystems. We found that species richness and plant communities in a forest farmed from AD 50–250 vary with the intensity of former agriculture, are linked to long‑term soil chemical and structural changes, and suggest that these effects may be irreversible over historical timescales.

Abstract

In western Europe, forest area has been expanding rapidly since the 19th century, mainly on former agricultural land. Previous studies show that plant diversity differs between these recent forests and ancient forests that were already forested at the time of first national cadastral surveys, around 1800. Here, we investigated the duration of such agricultural aftereffects. In northeastern France, large areas were deforested during the Roman occupation and thereafter abandoned to forest. In one such forest that was farmed during the period AD 50–250, we show that species richness and plant communities vary according to the intensity of former agriculture. These variations are linked to long-term changes of chemical and structural soil properties. Hence, we suggest that such effects of past agricultural land use on forest biodiversity may be irreversible on an historical time scale.