On the Use of Sap Flow Measurements to Assess the Water Requirements of Three Australian Native Tree Species

Abstract

The measurement of sap movement in xylem sapwood tissue using heat pulse velocity sap flow instruments has been commonly used to estimate plant transpiration. In this study, sap flow sensors (SFM1) based on the heat ratio method (HRM) were used to assess the sap flow performance of three different tree species located in the eastern suburbs of Melbourne, Australia over a 12-month period. A soil moisture budget profile featuring potential evapotranspiration and precipitation was developed to indicate soil moisture balance while the soil-plant-atmosphere continuum was established at the study site using data obtained from different monitoring instruments. The comparison of sap flow volume for the three species clearly showed that the water demand of Corymbia maculata was the highest when compared to Melaleuca styphelioides and Lophostemon confertus and the daily sap flow volume on the north side of the tree on average was 63% greater than that of the south side. By analysing the optimal temperature and vapour pressure deficit (VPD) for transpiration for all sampled trees, it was concluded that the Melaleuca styphelioides could better cope with hotter and drier weather conditions.

In situ monitoring of the impacts of Melaleuca styphelioides transpiration on soil water dynamics in an urban environment

“…Various scientific studies on tree transpiration have been performed using SFM1 because it can accurately measure tree water use [4,17,18,19,20]. One benefit of utilizing SFM1 is its ability to be deployed on-site without first calibrating the sensors.…”

Sap Flow Velocity in Fraxinus pennsylvanica in Response to Water Stress and Microclimatic Variables

“…Previous studies indicated that R s and VPD are the main factors that influence transpiration in a single tree in terms of meteorological factors affecting plant sap flow ( Deng et al, 2021 ). Another study indicated that solar radiation is the maximum impact factor and potential evapotranspiration and solar radiation are positively correlated with relative changes in the sap flow volume of plants with an R 2 of 0.75 ( Sun et al, 2021 ). However, the degree of influence of meteorological factors on sap flow varies for different moisture conditions.…”