Forest re-growth on medieval farmland after the Black Death pandemic—Implications for atmospheric CO 2 levels

Abstract

Well-dated pollen assemblages from an organic-rich infill of an oxbow lake of the river Roer (southeastern Netherlands) provide a high-resolution reconstruction of regional vegetation development and land-use for the period between AD 1000 and 1500. Regional effects of the mid-14th century plague pandemic known as the Black Death are reflected by a period of significant agricultural regression between AD 1350 and 1440. Concomitant re-growth of forest indicates the existence of a terrestrial carbon sink following the Black Death pandemic. A direct temporal correlation of the reconstructed changes in land-cover with a proxy record of atmospheric CO 2 mixing ratios based on stomatal frequency analysis of Quercus robur leaf remains suggests the coupling of long-term CO 2 trends of the 13th–15th centuries and coeval trends in regional forest density. During the period of maximum reforestation between AD 1400 and 1440, CO 2 levels seem to be relatively low, but the onset of a CO 2 decline may predate the spread of the Black Death in Europe.