Invasive Prunus cerasifera Ehrh. hosts more lichens than native tree species – does quantity reflect quality?

The impact of nonnative trees on epiphytic lichen diversity is one of the most significant knowledge gaps in invasion ecology. One notable invader, Prunus cerasifera Ehrh., has been identified as a rapidly spreading nonnative into forest ecosystems, potentially influencing the diversity of epiphytic lichens. The objective of this study was to determine whether the taxonomic and functional diversity of lichens colonizing P. cerasifera bark differs from that observed on native trees composing early successional oak-hornbeam forest. We conducted our study in the surroundings of the Białowieża National Park by surveying epiphytes inhabiting four native trees (Carpinus betulus, Tilia cordata, Quercus robur, and Populus tremula), and non-native P. cerasifera, varying in diameter at breast height (DBH). Using ordination and linear regression, we found that P. cerasifera hosted the highest taxonomic and functional diversity of lichens. For Q. robur and T. cordata we observed a positive relationship between increasing DBH and lichen taxonomic and functional diversity. Similarly, the epiphyte richness increased with DBH in P. cerasifera, but we did not find any relationship between lichen functional diversity and DBH. This suggests that even small P. cerasifera individuals can support a high epiphyte functional diversity, surpassing that of native trees. We provided novel evidence of invasive tree impact on the least analysed group of dependent organisms, broadening functional and phylogenetic range of assessed nonnative trees. In this context, P. cerasifera appears to play a specific function as a host of particular importance for restoring epiphytic biota in transformed ecosystems.