In forest succession studies, two major groups of tree species are usually recognized: pioneer and non-pioneer (climax) species. It is assumed that each group has its own set of adaptive traits that impart advantages or disadvantages to trees in early- and late-successional stages. In the present paper, the pioneer/climax concept is tested for 36 major European tree species, whose ontogenetic and ecological attributes (in total 21 variables) were compiled from the literature and analyzed by multivariate statistical methods. On this basis, a new ecological classification of tree species is proposed and interpreted in terms of the theoretical, triangular model of life-history strategies developed by Grime. For each type of life-history strategy (ruderal, stress-tolerant, competitive and intermediate), specific adaptations determining the functional roles of tree species in the dynamics of forest communities are identified and described.