Understanding the drivers of variation in water use of urban trees is essential to estimate and predict tree survival, health, and provision of ecosystem services now and in the near future characterised by more frequent droughts. Urban tree water status and water use vary within the urban mosaic of diverse microclimates and growth conditions, distinguished for example by the proportion of impervious surfaces that increase temperature but decrease water availability. We compared tree water status and water use dynamics between two urban environments in terms of impervious surfaces and microclimate: parks and streets. To do this, we tracked mid-day leaf water potential (WPMD) and sap flow in five common broadleaf deciduous species in Montreal, Canada, over two growing seasons (2020 and 2021). In both years WPMD and in 2021 sap flow were higher in the park than in street trees during the early summer. Yet, towards late summer 2021 dry periods and a cumulative deficit of precipitation decreased WPMD and sap flow among park trees, whereas street trees maintained relatively stable WPMD and sap flow. In conclusion, park trees were more vulnerable to dry conditions, while street trees appeared to be protected against drought potentially by more stable access to water or by water-use acclimations.

Les arts et les sciences, bien que différents dans leurs approches, partagent un objectif commun, celui d’explorer et de comprendre le monde. En croisant ces disciplines naissent des récits nouveaux, mêlant rigueur scientifique et sensibilité artistique. Petit bois, fruit d’une collaboration singulière entre une illustratrice et plusieurs scientifiques, offre un regard inédit sur la forêt boréale, convoquant émerveillement et savoir pour inviter à redécouvrir les écosystèmes forestiers.