This publication is the result of more than six years of hard work by a dedicated group of European urban forest and tree experts. The editors are indebted to the national experts of COST Action E12 ‘Urban Forests and Trees’ and to the others who have contributed to the various chapters in this publication. Ultimately, 59 authors from 21 European countries feature in this book. The European Cooperation in the field of Scientific and Technical Research (COST) and in particular its Secretariat deserve our gratitude for their support in establishing an active European community of urban forestry experts. In our work to prepare this publication, we have been assisted by Karen Sejr, who provided crucial editorial support. We are also grateful to Jette Abel, Birgit Brynjolf, Jette Alsing Larsen, and other colleagues at the Danish Centre for Forest, Landscape and Planning, KVL. Without their contributions, the work could never have been completed. Words of gratitude also go to the publisher,Springer, who have supported the idea to publish a first European reference book on urban forests and urban trees from the very start, and who showed patience during the long production process.