Team : MEA

Coordinator :  SAUDREAU Marc  

Project link : https://anr.fr/Projet-ANR-21-CE22-0021

Project website : https://trio-climatologie-strasbourg.fr/

Context

The two major assets that make the tree a benefactor, particularly appreciated during hot weather, are the shade it provides to passers-by and facades as well as its ability to regulate the temperature of its foliage and the air surrounding it, via the transpiration mechanism.

General presentation

Transpiration is a physiological phenomenon by which a tree emits water into the air, in gaseous form, through the stomata of its leaves, in order to ensure photosynthesis and at the same time regulate its temperature. Transpiration also activates the circulation of sap which comes from the roots towards all the organs of the plant. However, the effect of the tree's environment on leaf transpiration remains poorly understood, particularly in urban areas. While the cooling effect of trees is no longer in doubt, it remains to be quantified, knowing that it varies over the course of a day and depending on atmospheric conditions. The study of the interactions between trees and their environment should make it possible to identify planting methods to improve the living conditions and comfort of city dwellers. It will also help answer a question that is becoming increasingly important in the context of global warming. Indeed, the trees that line our streets may not be able to withstand future weather conditions. What tree species should be planted, in what quantity, and in what configurations relative to buildings and roadways? In this project, which brings together more than 15 scientists from various backgrounds, we seek to reproduce the physical impact of buildings and street trees on the urban microclimate, using measurements and 3D modeling of the site. The main objective is to understand, and then better characterize, the physical impact of buildings and street trees of different species on the urban microclimatology. In Strasbourg, the tree heritage currently includes many species, among which some are more represented than others, such as lime trees and plane trees, for example. The hackberry tree, more widespread in Mediterranean regions, is interesting for its ability to withstand water stress and resist high heat. This is why the project focuses on street trees of 3 different species: lime trees, hackberry trees and plane trees, which line 3 adjacent streets in Strasbourg. To monitor and understand them, we equip these trees with a large number of devices and carry out thermal, meteorological, eco-physiological and geometric measurements for at least two years. These measurement campaigns constitute the first part of the project. The second objective of TIR4sTREEt is to develop a methodology aimed at merging the geometry of an urban scene with measured surface temperatures. The result of coupling all the data will be used, in a third objective of TIR4sTREEt, to validate estimates produced by microclimatic simulation tools, currently being developed in the consortium. It is planned, at the end of the project, that this set of data, both measured and simulated, will be made available to the scientific community.

Partners

SILVA Institut national de recherche pour l'agriculture, l'alimentation et l'environnement Nancy
EMS Service espace verts, Géomatique et connaissance du territoire et Eco Ter, Eurométropole Strasbourg
INSA Strasbourg - ICube Laboratoire des sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (UMR 7357)
PIAF Physique et Physiologie Intégratives de l'Arbre en environnement fluctuant
Unistra - ICube Laboratoire des sciences de l'Ingénieur, de l'Informatique et de l'Imagerie (UMR 7357)

Funding

Agence Nationale de la Recherche (ANR)