Epsilon Open Archive

Abstract

The main body of work in this thesis was to develop and test a working procedure for identification of new tree species and genotypes that holds the potential to diversify urban tree populations. This process has been set in context through a literature review which characterise species-specific information about the tolerance of trees to the environmental stresses in urban paved sites.
With a Scandinavian focus, a review of literature was made in order to characterise species-specific information concerning site tolerance for urban paved environments as it is disseminated in scientific papers, dendrology literature, books addressing plant use in urban environments, plant nursery catalogues. The information was evaluated against the requirements of urban tree planners which should ideally be; contextual; local, referring to existing urban plantings, specify the urban site type(s) for which a given species can be recommended, and include the full range of tree species that are well adapted to the urban paved environment in a given climate region. In the analysis of the literature, abundant restrictions and misleading guidance were apparent. The results showed that existing information is piecemeal and that most is either too general (dendrology literature) or too specific or contradictory (scientific literature) to meet the requirements of urban tree planners, while books intended for plant use in cities do not sufficiently integrate the regional perspective. Moreover, contextual information local to the Scandinavian region is mainly provided for already much used species.
With a focus on the northern parts of Central Europe and the adjoining milder parts of Scandinavia (CNE-region), a working procedure for the identification of potential tree species and genotypes for in inner-city environments was developed. The procedure was made through two case studies; in the Qinling Mountains, China, and in north-east Romania and neighbouring parts of the Republic of Moldavia. In total, 27 tree species were identified as tolerable for warm and periodically dry habitats. Of these tree species, only four are currently much used or used to some extent in northern Europe. Accordingly, the reaming 23 tree species identified hold potential to supplement and diversify the urban tree populations in the CNE-region.