SLAMKA Ľuboš: Inter- and intra-species interactions among plants in their juvenile and mature stage of ontogeny in oak woods. [Bachelor thesis]. Technical University in Zvolen. Faculty of Forestry. Department of Phytology. Consultant: doc. Ing. František Máliš, Phd. Academic degree: Bachelor. Zvolen: TUZVO, 2021. 68p. In the focus of the bachelor thesis are the interrelations among various species of plants in terms of inter- and intra-species interactions. The main aim of the thesis is to explain the influence of the process of facilitation and competition on the natural recruitment regeneration and also the mutual influence among the individual development stages in the process of ontogeny. Knowing these relations between the plants in the process of regeneration can help better to understand the development of recruits in the given environment, as well as to take suitable measures when growing and managing the coppice. The studied locality was in this case situated in the lower areas, where local oak woods are due to their structure suitable for the study of the subject matter. As expected, in the original coppice assemblage, the sessile oak prevailed over the beech. Furthermore, there were also English and Turkish oaks found in the studied localities. As concurrent plants in those coppices were found species of maple and lime, but also wild service tree, hornbeam and ash tree. The data collection was realized on the basis of an external methodology, which provided a definition of the data collection process and the description of the individual development stages. The data was collected on randomly selected localities, where the process followed strictly defined transect, and consequently processed in Microsoft Excel. Then, charts were generated in the R program which showed the relations among various variables. The final outputs contained only the frequent trees. The study results from this thesis proved that there are interactions among individual species, specifically from the seedling stage up to the mature tree, where highly important are their inter- and intra-species interactions. The study also proved that the needs of the juvenile plants as for the environment factors differ. The ontogeny offsets in the niches and the inter- and intra-species interactions mutually influence the development and survival of the seedlings. The crucial finding is that there is a connection between a seedling and a mature tree, because the level of regeneration of a natural recruitment was higher around the mature trees. The competition as well plays an important role in the natural recruitment regeneration. The influence of the competition on the species during ontogeny has been confirmed among the plants of the same as well as different species. The above proved that there is an ongoing struggle for living space in plant communities in every stage of ontogeny. Keywords: oak woods, niche, ontogeny, inter-species interaction, intra-species interaction