To combat climate change and increase the extent of the canopy, the City of Geneva has adopted a proactive policy of tree planting. The planting target for next year has been set at 600 trees to meet the commitment of tripling the number of trees planted in relation to those felled. The lines of trees on Quai Capo-d’Istria and rue Saint-Léger have been completely revised.
In order to meet the commitment to replace each tree felled with three new trees, the Parks and Gardens Service planted 912 trees between November 2021 and April 2022. The target of 900 trees planted has therefore been exceeded. This massive planting effort, which represents one of the tools for addressing the climate emergency will be pursued in order to contribute to increasing tree coverage from 21% in 2020 to at least 25% of the municipal territory in 2030.
In two seasons, some 1,445 trees have been planted compared to an average of 150 to 200 per year in the past. To meet the objectives, the Parks and Gardens teams have ramped up their efforts. This policy involves more interventions as well as increased logistics in both human and material terms, as the young trees require particular care during the first three years after planting, especially with regard to watering. The white pain or the bamboo lath surrounds around the young trees protect them in the event of heatwaves.
A remarkable variety
The wide variety of species planted serves to test their resilience while fostering biodiversity and developing the exceptional variety of the City’s tree heritage. Among oaks alone, a dozen species have been selected, such as the holly oak, the Vilmorin’s oak or the very elegant chestnut-leaved oak. A dozen species of maple as well as Mediterranean hackberry trees and Japanese pagoda trees have also been chosen. All the trees are adapted to climate change.
Some 700 trees have been planted in the city’s parks and a further 200 in the streets, squares and school yards in order to provide shade across the entire territory. The parks along the northern shore and Parc La Grange, which were severely affected by the storm in August 2019, have greatly benefited from the planting campaign. An orchard containing some thirty fruit trees – plum, quince, cherry and apple trees – has been planted in the Domaine de l’Impératrice.
Two lines of trees have been revisited, with the addition of 11 honey locust trees on Quai Capo-d’Istria and 8 Japanese pagoda trees in rue Saint-Léger. The trees are now connected to one another by continuous underground trenches, offering the roots more soil. A permeable soil – clay-limestone for the former and paved for the latter – offers enhanced infiltration of rainwater to enhance the irrigation of the trees, with their bases surrounded by annual flowers. A new line of 5 holly oaks has been planted in rue du Grand-Pré.
Planting target for next year
For the 2022-2023 season, the planting target has been set at 600 trees to offset the felling of 197 individual trees between 1 June 2021 and 31 May 2022. More specifically, 106 trees were dead (54%), 43 were deemed dangerous (22%), 41 dying (suffering from advanced and irreversible physiological problems - 21%), 5 had fallen sue to storms and 2 were subject to incidents. There were no major storms during the past year, which limited the number of fallen trees.
The species most affected are elms, maples, plane trees, beech trees, prunus and birches. Since the 1970s, elms have suffered from Dutch elm disease, which is caused by a particularly virulent vascular fungus and exacerbated by climate change. Maples, beeches, prunus and birches are also affected, in particular by the lack of regular water. “We have noted a clear increase in and acceleration of the effects of climate change on the city’s tree heritage, which has become more vulnerable. This requires not only more trees to be planted so that we can adapt to the situation, but also greater care to be given to the tree heritage in order to ensure its conservation,” stresses Alfonso Gomez, Executive Councillor responsible for the Environment.
The plants are much more resilient, but several trees were very old and displayed rot and changes in their trunks and scaffold branches, making it impossible to maintain them. Furthermore, in wooded areas, 21 trees had to be felled. They will be replaced by natural regeneration.
More information on tree management.
Article modifié le 22.06.2022 à 17:06