The Carolinian forest is a unique and highly diverse ecosystem in the Great Lakes region and eastern North America. It is dominated by deciduous broad leaf forest species, many of which are under stress due to climate change and threatened by land use changes. In this study we explore and quantify interspecific differences in transpiration and water use in seven Carolinian tree species including six broadleaf deciduous species (Acer rubrum, Populus grandidentata, Prunus serotina, Quercus alba, Quercus rubra, and Quercus velutina) and one needleleaf conifer (Pinus strobus) using sap flow and ecosystem level eddy covariance fluxes. Our study site (CA-TPD, CanFlux and Ameriflux notation) is a 90-year-old regenerated but managed Carolinian forest, located in the Long Point region, north of Lake Erie in Southern Ontario, Canada. Sap flow was monitored in 44 trees using Granier-style thermal dissipation sensors in 2023 and 2024. Year-round eddy covariance fluxes were also measured over this period on top of a 36 metre scaffolding tower proving ecosystem level water balance and water use efficiency. We found large differences in sap flow and transpiration among the studied tree species, providing insights into water use and water conservation strategies utilized by these tree species. These findings will provide insight into species-specific water-use and help identify which tree species may be better adapted to future climate change and shifting water availability in the Great Lakes region.