Exotiska trädarter i urbana miljöer : fördelar, nackdelar och risker kopplat till användningen av exotiskt växtmaterial i urbana miljöer

Abstract: The design of our outdoor environments is today an important part of a functioning city. The cities are growing more densely and the green areas are getting smaller. This means that the presence of vegetation and especially trees in urban environments is of great importance. Trees are an important part in the city and contribute with a number of different positive effects. To create a sustainable future for Sweden's urban tree population, an expanded and adapted plant material is required. The purpose of the study is to investigate the advantages, disadvantages and risks associated with use of exotic tree species in urban environments and examine 22 Swedish municipalities and their attitude towards the use of exotic tree species. The study partly includes a literature study and partly a questionnaire survey. The literature study describes the role of trees in the city and how art diversity is a major component for creating resilient tree populations. The use of exotic tree species extends the use and serves as a complement to the domestic plant material. The city as a plant site is challenging, but many exotic tree species originate from areas that resemble the dry and warm conditions of the city and are therefore well suited as city trees. However, the use of exotic plant material is associated with risks, but most introduced species, have low, or even no risk if used under the right conditions. The survey includes 22 Swedish municipalities. Five questions were sent to each municipality to find out their attitude towards the use of exotic species, if species diversity is prioritized, the use of untested introduced species and if climate change are considered when selecting tree species. Furthermore, the responses of the participating municipalities are summarized and discussed. Finally, the advantages and disadvantages of the use of exotic tree species are discussed. There are both risks of using and excluding exotic tree species. Exotic tree species in combination with domestic species create better conditions for adapting tree species in urban environments, contributing to a greater choice when designing outdoor environments and contributing to a greater variety of species. Which creates sustainable and resilient urban tree forests.