Street trees and urban forests refer to the trees and wooded areas within urban environments. The trees and the forested areas are planted and/or strategically conserved in cities to provide ecological, social, aesthetic and economic benefits.  

Street trees are often chosen based on their ability to thrive in urban conditions, including tolerance to pollution, limited soil space, and varying moisture levels. Urban forests can usually support a wider variety of tree species and understorey vegetation, contributing to greater diversity and urban biodiversity. 

Street trees and urban forests can be found throughout city areas, from centres to sub-urban neighbourhoods. Their placement is influenced by factors such as available space, soil conditions and planning goals. Street trees are typically planted along roads and sidewalks, while urban forests can also be placed in parks, riverbanks and other green areas in the city.   

Why 

Street trees and urban forests contribute to addressing several societal challenges, including: 

ATTENTION! 

The success of street trees and urban forests depends on careful planning and ongoing maintenance. Challenges, such as ensuring tree survival in harsh urban conditions, preventing damage to infrastructure and managing conflicts with utilities also makes community engagement and education relevant.  

When planting trees, it is preferable to use native species. It is essential to be mindful of the use of invasive species. In Nordic cities trees planted along roads are often exposed to road salt, so this should be taken into consideration when choosing species for such locations.  

Urban areas are dynamic places and during their lifetime the conditions for trees may change. These changes should be paid attention to and developments that present sudden changes to the trees living conditions should be remediated to enable the tree to adapt and restore and keep vitality. Strategies, laws, and other instruments are also essential for conserving mature urban trees. 

When it comes to maintenance, cutting and pruning of mature trees is sometimes necessary but needs to be done carefully to not damage the trees.  

Extensive research and case studies show how street trees and urban forests contribute to the urban environment. Studies highlight these NBS’ role in climate resilience, biodiversity and human health. Recent research also show that the effects on air quality might be more complex than previously thought (Venter et al. 2024). Ongoing research and projects explore best practices for selecting, planting, and maintaining trees in various urban contexts in the Nordics.  

Costs

Planting and maintaining street trees and urban forests vary widely based on site preparations, tree species, maintenance requirements and labour costs.