Located in the heart of the schooltwo charms, a plane tree, three oaks and a redwood, all dead or declines, have become dangerous* and must imperatively be slaughtered. The follow -up of their health state undertaken several years ago has noted two independent expertise mandated by the Seve within the framework of its mission of management of the tree heritage of the city.
Thus, in September 2024, a bureau d’expertise In trees management has carried out a health and security diagnosis of each of the 80 specimens located within the perimeter of the Genêts school. 12.5 % of these trees were proved to be in very poor condition. The seven trees mentioned above are the most affected subjects, with a negative evolution that has recently accelerated.
Even -appeal expertise
Given the remarkable character of two old oaks, a new expertise was carried out on June 16, 2025 in order to assess the evolution of their health state and to quantify the risk. These trees were analyzed with tools to precisely measure their healthy wooden portions. The result is final. The presence of large internal cavities and lignivorous mushrooms, signs of advanced degradation of fatal wood for the trunk and the roots, were noted, as well as a very insufficient healthy wood thickness, making the intervention to be carried out.
The redwood presents a irreversible decline of more than 70% of the crown, mainly due to the attack on a fungus. The latter leads to the progressive drying up of the branches and the interruption of the circulation of the sap, causing the death of the affected parts. Despite the various security measures implemented by the Seve (protective perimeter and hacking of almost all main branches), scraps of branches in the middle of the courtyard cannot be excluded. If the tree remains imposing by its size, it is today almost dry, its decline having been accelerated by recent droughts and successive heat waves.
The risk of falling Of these trees, evaluated according to the QTRA ** method, is considered to be very high. Given the high frequentation of the site during school hours but also outside these, especially during weekends and holidays, no measure allowing to keep trees reasonably being considered.
Interventions brought to multiply
A what stands, a protection perimeter was installed around the trees concerned to secure the area. The work will start on July 9, 2025 and will spread over about a month, so as to be finalized before the start of the school year.
Of the replantations will take place during the winter of 2025-2026, with the introduction of young trees adapted to the place, in order to guarantee the continuity of plant cover and preserve biodiversity. Natural regeneration will also be favored in certain areas. Part of the trunks will be maintained on site in the form of “skittles” to promote local fauna. The remains of the slaughtered trees will, when possible, transformed into chips reused with broom or in other schools of schools.
In addition, on Thursday, July 3, a spruce with a marked inclination and a significant cracking of its trunk had to be shot in emergency in Bertrand park, while a similar intervention had to be carried out this Friday morning on a large oak on Chemin de la Chevillarde. In view of the climatic conditions and their impact already found on the plant heritage, a multiplication and intensification of this type of interventions are to be feared in the future.
* A recognized dangerous tree is a tree whose mechanical or physiological state represents a high risk of rupture or fall.
** The QTRA method is a method of quantitative assessment of arboreal risk, which expresses the annual probability of a dangerous event.
