Riparian plant water relations along the north fork of the Kings River, California

Plant water relations of five obligate ripar-ian species were studied along California\u27s North Fork Kings River. Diurnal stomatal conductance, transpi-ration, and xylem pressure potentials were measured throughout the 1986 growing season and in mid-season in 1987. Patterns were similar for all species although absolute values varied considerably. Maximum stomatal conductance occurred early in the day and season during favorable environmental conditions and decreased as air temperature and the vapor pressure difference between the leaf and air increased. Maximum transpiration rates occurred in mid-morning and mid-summer resulting in estimated daily water losses per unit sunlit leaf area of 163-328 mol H2O m-2. Predawn xylem pressure poten-tials remained high in 1986 when streamflows averaged 1.41 m3/s (50 cfs), however they were notably lower in 1987 at 0.7 m3/s (25 cfs)