Title of Dataset: Data from: First-year Acacia seedlings are anisohydric Ôwater-spendersÕ but differ in their rates of water use. Data were collected in a glasshouse at Wake Forest University during 2018-2019, and from Serengeti National Park, Tanzania, from 2015-2019. For questions, contact Scott Cory (coryst15@wfu.edu). Five files are included: File ÒLicor.df.csvÓ: Gas exchange data, leaf water potentials, soil water potentials, and calculated values of Hydraulic Conductance and Percent Loss of Conductance. PlantID is the identify of each plant, numbered 1-10 for Acacia robusta, and 26-35 for A. tortilis. Date_as.Date is the date of gas exchange measurements, in the format of mm/dd/yy. MeasurementDate are the same dates, but in the format Mon dd yyyy. Obs is the observation number of a particular day of measurements with the Licor 6400 gas exchange system. Time is the number of seconds since the log file was created on the licor. All gas exchange measurements are expressed on a leaf area basis, and leaf temperature was calculated by an energy balance approach. Photo is photosynthesis in umol m-2 s-1. Cond is stomatal conductance in mol m-2 s-1. Ci is concentration of CO2 inside the leaf. Trmmol is Transpiration in mmol m-2 s-1. VpdL is the vapor pressure deficit, based on air temperature inside the licor chamber and calculated leaf temperature. Area is the leaf area in cm^2. StmRat is the stomatal ratio. BLCond is the boundary layer conductance, in mol m-2 s-1. EBTlf is the leaf temperature in Celcius, which was calculated on an energy balance approach. Tair, Tleaf, and Tblock are temperatures of the Licor (measured with thermocouples). CO2R and CO2S are the concentrations in CO2 in the sample and reference IRGAs. RH_R and RH_S is the relative humidity in %. Flow is the flow rate through the chamber. PARi and PARo are photosynthetically active radiation inside and outside of the licor, in umol m-2 s-1. MeasurementNumber refers to order of the sampling date. WaterPotential_bars is the Leaf Water Potential of the same leaf as licor measurements, using a Scholander-style pressure chamber. LeafArea is the leaf are inside the licor chamber, in cm^2. Date_as.POSIX is the date of measurements, in the format mm/dd/yy. Species.x and Species.y are the species identity of each PlantID. DayNumberOfExperiment is the number of days since the seeds were sown. WaterPotentialSensorNumber, LoggerNumber, and PortNumber refer to the Soil water potential sensors, and were used to orient each individual plant with its corresponding sensor. SWP is the soil water potential in kPa, measured with MPS-6 (=TEROS 21) sensors (Meter Group) buried in each pot. WaterPotential is the leaf water potential in MPa. SWP_MPa is the soil water potential in MPa. HydraulicConductivity is the whole-plant hydraulic conductance in mmol m-2 s-1 MPa-1. Kmax_OfAllMeasurements is the maximum hydraulic conductance of each particular plant, which was used to calculate the percent loss of conductance for subsequent Kplant measurements for each plant. PLC is the percent loss of conductance, relative to the maximum hydraulic conductance of each plant. File ÒLoggers_Subset_Truncated_Robusta.csvÓ: Soil water potential (SWP) in kPa, measured with TEROS 21 sensors. These data were used to construct Figure 1A. In each pot, sensors were buried at a depth of 23cm from the top of the pot prior to sowing seeds. On each particular day, we extracted Soil Water Potential values at 6am EST, as this was the time of day when the sensor temperature was most stable. Date is the date of each measurement in mm/dd/yy. TimeStamp is the date and time (of each measurement). ID_x corresponds to the PlantID in ÒLicor.df.csvÓ. AverageSWP is the average SWP of all plants, in kPa. SE is the standard error of the mean SWP. DayNumber is the number of days after seeds were sown. AverageSWP_MPa is the SWP in MPa. File ÒLoggers_Subset_Truncated_Tortilis.csvÓ: Soil water potential (SWP) in kPa, measured with TEROS 21 sensors. These data were used to construct Figure 1A. In each pot, sensors were buried at a depth of 23cm from the top of the pot prior to sowing seeds. On each particular day, we extracted Soil Water Potential values at 6am EST, as this was the time of day when the sensor temperature was most stable. Date is the date of each measurement in mm/dd/yy. TimeStamp is the date and time (of each measurement). ID_x corresponds to the PlantID in ÒLicor.df.csvÓ. AverageSWP is the average SWP of all plants, in kPa. SE is the standard error of the mean SWP. DayNumber is the number of days after seeds were sown. AverageSWP_MPa is the SWP in MPa. File Òacarob.dat.csvÓ: Species distributions and field measurements of soil water potential, for the analysis in Appendix S2. SITE refers to each of the seven long-term field sites. TREE.COUNT is the abundance of adult trees > 5 cm DBH and > 2 m in height in 1000 m^2 plots (all species combined). SP.COUNT is the abundance of just one species (in this case, A. robusta). SP.PROP is the proportional abundance of the species, relative to TREE.COUNT. DRY.DAYS is the calculated number of dry-down days. File Òacator.dat.csvÓ: Species distributions and field measurements of soil water potential, for the analysis in Appendix S2. SITE refers to each of the seven long-term field sites. TREE.COUNT is the abundance of adult trees > 5 cm DBH and > 2 m in height in 1000 m2 plots (all species combined). SP.COUNT is the abundance of just one species (in this case, A. tortilis). SP.PROP is the proportional abundance of the species, relative to TREE.COUNT. DRY.DAYS is the calculated number of dry-down days.