In the face of global change, biodiversity has been put forward as a strategy for the adaption of forests given its positive correlation with productivity. However, a greater forest productivity often goes along with increased water use by trees, which can in time lead to water stress for trees. Very few studies have examined how biodiversity influence water fluxes in forests. The objective of this project is to understand the effect of species diversity on tree transpiration. The project was conducted at the IDENT (International Diversity Experiment Network with Trees) experimental site in Sainte Anne de Bellevue (Quebec, Canada). Tree transpiration was measured during two growing seasons in 2022 and 2023 using Heat Pulse Velocity (HPV) sap flow sensors that were deployed on 44 trees belonging to four species native to North American temperate forests (Acer rubrum Marsh., Betula alleghaniensis Britton., Betula papyrifera Marsh. and Quercus rubra L.). The sampled trees were distributed in monocultures and mixtures of two species and four species. Given the importance of the influence of weather conditions on transpiration, air temperature and humidity were also measured throughout the growing season. Soil moisture was monitored using sensors measuring the soil water potential and volumetric water content. For each species, the sap flux density of trees growing in monocultures will be compared to the sap flux density of trees growing in mixtures. Results of this project will provide a better understanding of how certain management measures promoting biodiversity could affect water resources in forests.