Subtle human impacts on neutral genetic diversity and spatial patterns of genetic variation in European beech (Fagus sylvatica)

We aim to understand the role of past and ongoing anthropogenic impacts on genetic variation patterns at different spatial scales for the dominant tree species European beech (Fagus sylvatica L) in Germany, a densely populated country with a long history of multiple human impacts on forests. Different types of human impact have likely influenced genetic variation patterns in beech: e.g. forest degradation and loss of forest cover over long time periods, intensive management and climate change. Former studies found generally high genetic diversity in European beech and indicated, based on limited sample sizes and few markers, no negative effects of management on genetic diversity. We investigated 30 beech stands with different management history located in three widely separated regions in Germany at six genomic and three gene-based microsatellite markers. High genetic diversity was found, but diversity levels were significantly different among regions. Genetic differentiation among stands and regions was generally low, but significant for most comparisons. The region in southern Germany was strongly differentiated from the other regions presumably due to different postglacial recolonization histories. Recent management activities had no significant impact on genetic diversity parameters but reduced small-scale spatial genetic structures (SGS) within stands. Long generation times, large effective population sizes, efficient gene flow and predominance of natural regeneration contributed to the maintenance of high genetic diversity throughout the Central European distribution of beech. Genetic diversity patterns of beech are remarkably unaffected by human impact although forested landscapes were strongly shaped by man for centuries. (C) 2014 Elsevier B.V. All rights reserved.