Simulating functionally diverse forests of different biomes where environmental filtering is strong, is a challenge for flexible-trait DGVMs. We adapt LPJmL-FIT to the European biomes and use model output to validate PFT distribution, structural and physiological variables as well as trait distributions. Theory on functional diversity states that climate is the first filter for selecting surviving strategies (environmental filtering) and leads to convergence of functional traits. Where climatic stress is reduced, biotic interactions, e.g. competition, become more important allowing for higher functional divergence. We compute functional diversity (functional evenness, functional divergence, functional richness) from simulated plant traits. We find that the influence of climate vs. plant competition is reflected differently in functional diversity indices, thus resulting in different spatial pattern. We then discuss how flexible-trait DGVMs can be used to test biodiversity-ecosystem functioning hypotheses and to inform conservation planning to enhance functional diversity in European forests.