Internal Water Balance of Brigalow (Acacia harpophylla F. Muell.) Under Natural Conditions

Abstract

On one day each month over a period of 2½ years, diurnal measurements of plant water status, leaf diffusive resistance, carbon uptake, irradiance, ambient temperature and humidity were made in a brigalow community. Diurnal changes in leaf diffusive resistance, osmotic potential, plant water potential, and carbon uptake are shown to follow general patterns and the changes in plant water potential were related to the dawn value of plant water potential. The data suggest the development of negative turgor in brigalow and demonstrate the capacity of the plant to maintain high tissue water contents at low water potentials. Measurements of shoot extension and litter fall showed that litter fall occurred principally following shoot extension.