Edited by Barbara A. Schaal, Washington University, St. Louis, MO, and approved March 6, 2006 (received for review November 22, 2005)
Habitat fragmentation poses a serious threat to plants through genetic changes associated with increased isolation and reduced population size. However, the longevity of trees, combined with effective seed or pollen dispersal, can enhance their resistance to these effects. The European beech (Fagus sylvatica) dominates forest over large regions of Europe. We demonstrate that habitat fragmentation in this species has led to genetic bottlenecks and the disruption of the species' breeding system, leading to significantly elevated levels of inbreeding, population divergence, and reduced genetic diversity within populations. These results show that, in contrast with the findings of previous studies, forest fragmentation has a negative genetic impact, even in this widespread, wind-pollinated tree. The identification of significant effects of forest fragmentation in beech demonstrates that trees are not at reduced risk from environmental change. This should be accounted for in the management of remaining natural and seminatural forest throughout the world.
Author contributions: A.S.J. and J.P. designed research; A.S.J. performed research; A.S.J. analyzed data; and A.S.J. and J.P. wrote the paper.
↵ † F is ≠ 0, α = 0.05 after Bonferroni correction, 480 randomizations; F3 and F4 denote the sample number.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
