Genetic implications of environmental stress in adult forest stands of Fagus sylvatica L.

Abstract

Results of a multilocus scoring of genotypes in six adult stands of the European beech (Fagus sylvatica L.) subjected to prolonged air pollution are surveyed. In each stand, the genetic comparison based on pairwise selected “tolerant” and “sensitive” trees revealed statistically significant differences between the genetic structures of the two subpopulations. A small part of the genic multiplicity is represented only in the “sensitive” subpopulations and is thus endangered. The “tolerant” subpopulations contain a considerably greater amount of genetic variation (hypothetical gametic multilocus diversity) than the “sensitive” ones. This phenomenon is less pronounced at the level of the actual and conditional heterozygosities. The heterogeneity of environmental stress conditions generally seems to cause a very complex reaction at the multilocus level in favour of preservation of genetic variation rather than directed viability selection at single loci. Consequences for the maintenance of adaptive abilities of forest tree populations are briefly outlined.