INVESTIGATIONS ON VITALITY AND GENETIC-STRUCTURE IN OAK STANDS

Six oak stands with the two indigenous species Quercus petraea and Q r obur were investigated in order to establish relationships between the vitality of oak trees and their genetic structure. The stands were af fected by the 'European oak decline'. The registered traits of every t ree were branching habits, defoliation, discoloration of foliage, necr osis on stems, epicormic branches at stems and in the crowns. The seve ral traits were integrated into a vitality coefficient. Isozyme analys es were carried out to characterize the genetic structure of oak stand s and subpopulations distinguished by their vitality. In principle, th e results indicate the same tendency for the relationship between vita lity and genetic structure for Q robur and Q petraea: increase of exce ss of homozygotes from the tolerant group to the sensitive group, decr ease of observed heterozygosity from the tolerant to the sensitive gro up, maximum hypothetical gametic diversity and minimum subpopulation d ifferentiation in the intermediate group as an indication for a direct ed selection.