REVEGETATION OF A SCALDED SALINE DISCHARGE ZONE IN CENTRAL QUEENSLAND.2. WATER-USE BY VEGETATION AND WATER-TABLE DRAWDOWN

The hydrological effect of Casuarina glauca trees established on a sal t pan in East Barmoya, Central Queensland, is described. The sap flow of a single (4-year-old, 5 m tall) tree was logged with the steady-sta te heat balance technique at about 11 L/day. The watertable adjacent t o the tree was depressed by about 130 mm relative to that 10 m from th e tree, and demonstrated a diurnal oscillation of about 10 mm, consist ent with an evapotranspiration rate of 1 mm/day. Infiltration was rapi d in the vicinity of the tree, such that the watertable rose quickly ( about 10 mm/h) in the vicinity of the tree after rainfall events. An a pparent response of the watertable to changes in barometric pressure w as also noted. The density of tree planting required to halt dryland s alinity on this site was estimated, and a density trial was commenced with the aim of lowering the watertable to enable the re-establishment of pasture communities between the rows in a form of agroforestry.