European forest cover during the Holocene reconstructed from pollen records.

Abstract

Changes in tree cover influence many aspects of the earth system. Recent regional changes in tree cover, as documented by remote-sensed observations, are insufficient in capturing the response to large climate changes or differentiating the impacts of human activities from natural drivers. Pollen records provide an opportunity to examine the causes of changes in tree cover in response to large climate changes in the past and during periods when human influence was less important than today. Here, we reconstruct changes in tree cover in Europe through the Holocene using fossil pollen records, using the modelled relationship between observed modern tree cover and modern pollen samples. At a pan-European scale, tree cover is low at the beginning of the Holocene but increases rapidly during the early Holocene and is maximal at ca. 6500 cal. BP, after which tree cover declines to present-day levels. The rapidity of the post-glacial increase in tree cover and the timing and length of maximum tree cover varies regionally, reflecting differences in climate trajectories during the early and mid-Holocene. The nature of the subsequent reduction in tree cover also varies, which may be due to differences in climate but may also reflect different degrees of human influence. The reconstructed patterns of change in tree cover are similar to those shown in previous reconstructions. Our approach is relatively simple and only requires readily available data; it could therefore be applied to reconstruct tree cover globally.