Helsinki tree trial unveils five new street tree species for climate adaptation

Helsinki’s tree trial has revealed five new potential street tree species. In 2012, the city’s arborists planted 44 saplings representing 13 new tree species in Vartiokylä. The aim was to monitor how these species adapt to climate change and to see if they could thrive in Helsinki’s climate, compared to their success in other Northern European cities.

Juha Raisio, a tree expert in Helsinki, notes that if such species had been suggested 25 years ago, they would have been considered eccentric. The results of the trial are now visible along Vartioharjuntie in East Helsinki.

Raisio reports that five of the species planted 12 years ago are thriving: they are the sweet cherry, the oak, the silver hawthorn, the hornbeam, and the blunt hawthorn. Over the next ten years, these species are expected to be increasingly integrated into Helsinki’s streets and parks. While these newcomers may not become dominant species, their use as street trees is likely to grow if they continue to adapt to the changing climate.

Other species from the trial will also be evaluated further to determine their suitability for Helsinki. Raisio emphasizes that trials in different growth environments are essential before making final assessments.

The five species poised to become future street trees in Helsinki include:

1. Sweet Cherry – A native of southern Scandinavia valued by carpenters. 2. Oak – Thrives with robust growth, suitable for wider spaces. 3. Silver Hawthorn – A compact, low-maintenance species. 4. Hornbeam – Ideal for narrow streets due to its bushy form. 5. Blunt Hawthorn – Suitable for narrow areas with a maximum height of around ten meters.

Raisio encourages cities across Finland to consider similar tree trials, highlighting the need for more diverse species in urban environments.