Predicted changes in precipitation and temperatures of the south central portion of the
Results show that a broad range of leaf water potentials exist ranging from -0.35 MPa to -7.10 MPa. Specific leaf water content values, the ratio of the mass of water in the fresh sample to the oven dry sample mass, also show a broad range of values (62 to 128 percent). Sap flux data measured at the same time indicate that J. ashei transpires at very low leaf water potentials, with a non-linear decline in flux values with decreasing leaf water potentials. The results of the systematic sampling indicate that leaf water potential was strongly correlated with leaf water content, as well as with vapor pressure deficit values calculated from temperature and relative humidity values measured at the time of sampling. Leaf water potential also correlated strongly with irradiance values. There were no significant differences observed in the leaf water potential - leaf water content relationship by canopy height leading to speculation about internal leaf morphological differences. Analysis of electron microscopy cross-sections of leaves collected synoptically at varying heights also indicate no difference with canopy height. These results concur with the findings of other water use studies of J. ashei and indicate that the species is likely to be a highly competitive species under future water limited conditions.