EN
Forecasted climate changes demand selection of populations (seed stands) and genotypes (plus trees) best adapted to changing environmental conditions and displaying limited genotype × environment (G×E) interaction. Analysis of multi-environment trials (METs) allows to recognize differences between populations and environments, as well as G×E interaction. To define stability of tree height we used a GGE biplot graphic method based on the results of measurement of 5- and 10-year-old trees originating from 30 European beech populations tested at three experimental sites. Majority of variance was explained in terms of the impact of environment. The studied environments were characterised by a similar discriminating ability and representativeness of growth conditions. Two mega-environments were identified as the studied populations of beech differed in their adaptation to local growth conditions. The analysed set of populations included those growing particularly well under the specific environmental conditions, and others displaying more general adaptability. The GGE biplot method is useful in breeding of forest trees.