While the tree heritage of the City of Geneva has suffered somewhat due to the heatwave and the long periods of drought and bad weather in recent months, the teams of the Parks and Gardens Service (SEVE) have been tasked with planting almost 600 specimens by spring 2023. Studies are also being conducted on the health status of the trees and the possibility of transforming parking spaces into planting areas.
Almost 600 trees will be planted within the municipality by the Parks and Gardens Service (SEVE) between November 2022 and April 2023 in order to respect the commitment to triple the number of trees planted compared to those felled.
The SEVE has selected species which are resistant to water shortages and long periods of intense heat – hackberries, crepe myrtle, Japanese pagoda trees, evergreen oaks, hop hornbeam, Mediterranean pine trees, Italian maples and other fruit trees. Several large trees will also be planted in Saint-Georges and in Parc Bertrand. An orchard will be created in Parc Trembley, while the mound on Place Sturm (rue Ferdinand Hodler side) will be planted with 80 young trees (saplings), 50 shrubs and 500 perennials.
Accompanying development and improving conditions
The mass planting campaigns of the past two years (over 1,500 new trees within the municipality) need significant accompaniment, requiring more human and material resources.
The trees must be watered for at least three years before they are sufficiently resistant and self-reliant. The long heatwaves and periods of summer drought have had a major impact on these young trees. The teams of the SEVE have had to reorganise their schedule to take care of this additional watering.
The trees in the streets suffer the most. Lack of depth and space, low soil fertility and sever urban constraints are just some of the difficulties which are compounded by those associated with climate change. These elements remind us that it is essential to create better conditions so that young trees can grow and flourish.
Protecting the existing heritage
As well as planting trees, the SEVE has paid particular attention to protecting existing trees.
Targeted studies are conducted on the trees and the soil in Parc des Bastions and the Jardin Anglais, two very popular sites which host numerous events. The trunks, tops, branches and collars of almost 600 trees are examined by an independent expert. Soil analyses will complete this study at the beginning of next year once the ongoing winter events in these locations are over, in order to better understand the environment in which the trees are living.
The compacting and sealing of the soil is highly detrimental to healthy development and survival. It is therefore essential to consider our tree heritage in close relation to the soil in which they grow. Similarly, any wound represents an open door to pathogens, which can weaken the trees. The results of these studies will help implement a strategy designed to ensure a more respectful approach to these sites.
Studying potential plantations in the least shady neighbourhoods
Finally, with a view to increasing the areas where trees will be planted, the SEVE is conducting a pilot study on the potential for transforming parking spaces in Les Pâquis and La Jonction and on the potential offered by private plots of land scattered around the City.
“We must prioritise action in the neighbourhoods and de-clump wherever heat islands exist. The population isn’t looking for large-scale architectural works, but tangible actions which don’t take years to come to fruition,” notes Alfonso Gomez, Executive Councillor responsible for the environment.
The aim is to create ditches that are sufficiently large and continuous to allow the roots to develop so that the trees can flourish in the long run. Within the scope of this project, the first trees should be planted in autumn 2023.