Together with Dr Anna Łubek (Jan Kochanowski University in Kielce) and Prof. Martin Kukwa, we examined, how different levels of the Białowieża Forest ecosystem organization (i.e. substrate, tree phorophyte and forest community levels) shape the functional composition of lichens. We characterised the lichen functional traits (i.e. morphological, anatomical and traits describing abilities to secondary metabolites production) distribution patterns, as well as assessed their degrees of specialization in relation to each of the three levels of ecosystem organisation considered. We observed that the distribution of specific combinations of lichen functional traits was most strongly influenced by substrate type, in relation to which the traits expressed the highest degree of specialization. We also demonstrated that traits associated with sexual and asexual reproduction of mycobionts were characterised by the highest degree of specialisation to all three analysed levels of ecosystem organisation. On the other hand, thallus type, ascospores pigmentation and the ability to produce lichenized diaspores , i.e. soredia and isidia, were the traits for which we obtained the lowest degrees of specialization to occur on a specific substrate, tree species, or in forest community. Our results contribute to a better understanding of the role of the forest ecosystem structure in shaping the occurrence patterns of specific trait combinations, as well as the functional diversity of lichens. The paper has been published in the Forests journal (https://doi.org/10.3390/f12040485).