Individual participants presented chapters for a book on ‘Introduced tree species in European forests: challenges and opportunities' that is the main ouptut of the project In-Tree. Many valuable comments were provided during individual discussion sessions and constructive feedback on individual contributions as well as the whole proposed book was provided. In addition, the workshop extended the network of experts on the topics of introduced tree species, which is tremendously important for a successful progress of the book preparation as well as for future collaborative work. Photos highlighting the event may be found in Galleries.