Snowmelt water use at transpiration onset: Dataset

Most studies investigate tree water use during the growing season. However, we know little about the source of transpiration during spring onset when trees rehydrate and recommence transpiration. This repository holds high-temporal resolution isotopic (δ18O and δ2H) and hydrometric measurements collected in the spring of 2018 at the Boreal Ecosystem Research and Monitoring Sites (BERMS). Sampling was conducted prior, during and after snowmelt at the Old Black Spruce site (OBS; 53. 98 °N, 105.12 °W) and the Old Jack Pine site (OJP; 53.92°N, 104.69 °W). We did this to characterize tree water use and the timing of transpiration phenological changes from the three dominant tree species – jack pine (Pinus banksiana), black spruce (Picea mariana) and larch (Larix laricina). This composite dataset contains stable isotopic composition data (δ2H and δ18O) of more than 1300 water samples of precipitation, bulk soil collected at different depths in the soil profile, xylem from jack pine, black spruce and larch, and stream from the White Gull Creek. The data set also comprises high-resolution tree hydraulic information from stem radius change and sap flow from all three species. Finally, the repository holds environmental conditions during the sampling period, including soil volumetric water content and temperature at different soil depths, snow depth, air temperature and precipitation. This data was used to understand patterns in tree water use during spring onset and provide a mechanistic understanding of tree water use dynamics by combining isotope hydrology, tree hydrodynamics and phenology.