Revegetation of a scalded saline discharge zone in Central Queensland. 2. Water use by vegetation and watertable drawdown

Abstract

The hydrological effect of Casuarina glauca trees established on a salt 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-state heat balance technique at about 11 L/day. The watertable adjacent to the tree was depressed by about 130 mm relative to that 10 m from the tree, and demonstrated a diurnal oscillation of about 10 mm, consistent with an evapotranspiration rate of 1 mm/day. Infiltration was rapid 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 apparent response of the watertable to changes in barometric pressure was also noted. The density of tree planting required to halt dryland salinity 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.