Heat stress tolerance of urban trees

Urban landscapes are expanding at a fast rate and have a significant effect on climate, from local to city and regional scales. Due to the urban heat island effect, trees in urban areas are exposed to higher temperatures than trees in rural areas. In addition, increasing temperatures and recurrent heatwaves exacerbate the urban heat island effect, which could critically endanger tree survival at heat exposed sites in cities.


Tree species show different tolerance to heat stress, and individuals of a species may acclimate to a certain degree to their environment by growing more resistant tissue. However, we do not yet know how plastic foliar heat tolerance is, and how acclimation may modify tree responses to their environment.


In this project we aim to measure and map the temperature tolerance of urban tree species across several cities in Switzerland, including Geneva, Lausanne, Bienne and Neuchâtel. We will compare four of the most planted tree species and assess their plasticity in heat tolerance.

Probing leaves of urban trees for heat tolerance measurements. 
Probing leaves of urban trees for heat tolerance measurements. 
Carpinus betulus showing early leaf senescence during the heatwave in August 2023.

For more information contact Christoph Bachofen.