Summary Pedunculate oak (Quercus robur L.) is a species that is represented in the forest vegetation of Croatia in the floral composition of 19 communities, and within 2 it is an edificator species. Forest communities in which pedunculate oak is an edificator are: pedunculate oak forest with large jaundice (Genisto elatae-Quercetum roboris) and pedunculate oak forest with hornbeam (Carpino betuli-Quercetum roboris). The pedunculate oak forest with a large jaundice is the most famous floodplain of the pedunculate oak, which rarely periodically turns blue. It is a characteristic community of the lower reaches, and comes in the valleys of large rivers. Pedunculate oak forest with common hornbeam is a typical community of beams, ie the highest terrains of the lowland belt, because common hornbeam is a species that does not tolerate standing water and high groundwater levels. In the community Carpino betuli-Quercetum roboris there is an increased proportion of mesophilic species compared to the community Genisto elatae-Quercetum roboris, which is confirmed by Prilog 2 where certain diagnostic species of these two communities are determined. The latest research of oak communities has established its presence in the Dinaric area of Lika, which is very atypical. Vukelic et al. (2019) dealt with the issue of oak communities in the Dinaric area. The research determined the floral composition of Dinaric oak forests and came to the conclusion that it differs significantly from that in lowland oak forests. The results of the study resulted in the need for a comprehensive analysis of pedunculate oak communities with an emphasis on lowland areas. With this research, a statistical analysis of previously published relevés of communities with pedunculate oak as an edificator was conducted. A total of 273 phytocenological relevés were processed. Phytocenological relevés were entered into Turboveg in analytical form (Hennekens & Schaminée 2001). Cluster analysis was performed and multidimensional scaling was performed in Primer 6 (Clarke and Gorley 2001) to see the tendency to group the relevés. In order to determine the identity of the initially described subassociations, diagnostic species were determined based on fidelity values in Juice 7.0 (Tichý 2002). The studied communities are subassociations of the communities Genisto elatae-Quercetum roboris (aceretosum tatarici, carpinetosum betuli, caricetosum brizoidis and caricetosum remotae) and Carpino betuli-Quercetum roboris (typicum, fagetosum, quercetosum cerridis and tilietosum tomentosae). The analysis found that the relevés of certain associations / subassociations deviate from the typical description of associations / subassociations. One of the reasons for this is that these are very dynamic forest ecosystems and a number of phytocenological relevés represent progressive or regressive transitions between individual associations or subassociations. In the subassociation of a pedunculate oak forest with a large jaundice carpinetosum betuli an increased proportion of wetland species of Alnion inacanae and Alnetea glutinosae was established. The presence of wetland habitat species is a due to disturbed habitat conditions in the Carpino betuli-Quercetum roboris community. In the subassociation of carpinetosum betuli, the absence of mesophilic species (Veronica montana, Lamium galeobdolon, Paris quadrifolia, Polygonatum multiflorum, etc.) was determined, which Vukelic (2012) singles out as distinctive. Analysis of the subassociation Carpino betuli-Quercetum roboris typicum revealed that there are no characteristic species. The result is a dispersion of its relevés into clusters corresponding to the Carpino betuli-Quercetum roboris fagetosum subassociation and the Genisto elatae-Quercetum roboris caricetosum brizoidis subassociation, indicating disturbance within the Carpino betuli-Quercetum roboris community. The study of the floral composition of the subassociation Genisto elatae-Quercetum roboris caricetosum remotae revealed a significant participation of wet habitat species of Alnion inacanae and Alnetea glutinosae. The main difference in relation to the subassociation of carpinetosum betuli is the increased share of non-forest species of the order Molinio-Arrhenatheretea and the order Phragmiti-Caricetea elatae. Vukelić (2012) singles out the species Amorpha fruticosa, Carex riparia, Carex elata, Filipendula ulmaria, Lythrum salicaria and others as different species of subassociation of caricetosum remotae, which were not determined by this analysis. Analysis of the subassociation of caricetosum brizoidis in relation to other subassociations of pedunculate oak with large jaundice revealed species that do not have pronounced fidelity, which resulted in the coincidence of certain relevés with those of the subassociation Carpino betuli-Quercetum roboris carpinetosum betuli and caricetosum remotae. The overlap of certain relevés of the caricetosum brizoidis subassociation takes place because the taken relevés of this subassociation are located at the transition to these two subassociations. According to Vukelić (2012), the distinctive species of caricetosum brizoidis subassociation are Carex brizoides, Dryopteris carthusiana, Melampyrum nemorosum, Potentilla erecta, Veratrum album and others. In the subassociation Carpino betuli-Quercetum roboris fagetosum, the participation of mesophilic species of the order Fagetalia, species of the class Vaccinio-Piceetea and Aremonio-Fagion was recorded. determined. The absence of the species Luzula pilosa, Galium odoratum, Cardamine bulbifera, Oxalis acetosella, Sanicula europaea and Mercurialis perennis has been restablished, which Vukelić (2012) singles out as differentiating for the subassociation fagetosum. In the subassociations Carpino betuli-Quercetum roboris quercetosum cerridis and tilietosum tomentosae, an increased proportion of thermophilic species of the order Quercetalia pubescentis (Polygonatum latifolium, Fraxinus ornus, Cornus mas, Ruscus aculeatus and Viola hirta) was recorded. The presence of mesophilic species of the order Fagetalia and species of Carpinion betuli and Aremonio-Fagion connections within the tilietosum tomentosae subassociation were was not emphasized in the quercetosum cerridis subassociation. The brachypodietosum subassociation was originally classified as the Carpino betuli-Quercetum roboris typicum subassociation, and was analyzed as a separate association/subassociation with its own diagnostic species. The identified diagnostic species of this subassociation indicate altered habitat conditions within the Carpino betuli-Quercetum roboris community. For further analysis of associations/subassociations of pedunculate oak, it is necessary to coordinate the existing phytocenological relevés which are classified according to the author's determination in accordance with the analysis of this research.