Monitoring of trees with reliable technology is essential in phytoremediation. Sap flow instrumentation on three Eucalyptus species at a mine site in western Victoria, Australia, was used to determine which species is best suited to meet the goals of a phytoremediation project. Specifically, the aim of the monitoring was to determine which species could better tolerate the hypersaline soil, potentially lower saline ground water, and cope with expected hotter and drier weather given climate change scenarios. Over a summer period, average daily water use of E. cladocalyx was approximately six times greater than E. melliodora and four times greater than E. polybractea. During a three day heat wave event, E. cladocalyx was found to have a higher tolerance to extreme temperature. The optimal VPD/temperature for tree transpiration was 2.6 kPa/26.2 °C for E. cladocalyx, 2.1 kPa/23.9 °C for E. melliodora, and 2.0 kPa/23.2 °C for E. polybractea. Through sap flow monitoring, it was determined that E. cladocalyx could better tolerate saline soils, hotter and drier weather, and had greater potential to lower saline ground water.
Keywords: heat ratio method; heat wave; night-time transpiration; optimal VPD and temperature; tree water use.