Researchers test the holster on a street tree during the development trials.
Two consecutive dry years in South Australia have put extreme stress on urban trees and shrubs, with Flinders University experts examining degrees of dieback in Adelaide trees affected by the dry conditions.
To better understand how trees may respond to drought differently, the researchers used a novel approach to assess a plant’s ‘efficiency and safety’ (resilience) to take up water from the soil – in a sense measuring their ‘personality’.
“Some trees take up water from soil more efficiently than others when soil water is abundant, but become less safe in drought – just like humans with different personalities respond to different stressors,” says Professor of Hydrology Huade (Walter) Guan, explaining a new article in Hydrology and Earth System Sciences.
The article explains how different trees of the same species may develop some flexibility to adjust the trade-off between hydraulic efficiency and safety over dry and wet seasons.
“With this in mind, the tree ‘personality’ test to measure how the tree is responding during drought can help to determine whether it’s likely to recover when the soil moisture returns – and whether irrigation or watering is recommended, or too late to apply,” says Professor Guan, from the College of Science and Engineering.
“Knowing a tree’s ‘personality’ will be useful for councils and residents to take care of urban trees by retaining stormwater in soils for trees vulnerable in droughts.”
Current measurements of plant hydraulic properties are labour intensive, destructive and difficult to scale up – limiting the comprehensive characterisation of whole-plant and surrounding land-surface hydraulic properties.
The experimental trials were conducted on Allocasuarina verticillata, a flowering plant known as drooping sheoak endemic to south-eastern Australia, to develop the new, non-destructive method to easily test the trade-off between tree hydraulic efficiency and safety.
The novel system makes concurrent measurements of sap flow and water potential, using two small devices attached to a tree stem, like a Holter monitor for a human to record heart rhythms.
Flinders co-authors Professor Guan, PhD candidate Zhechen Zhang and Professor Okke Batelaan, from the National Centre for Groundwater Research and Training at Flinders University, worked with colleagues from the University of WA and Colorado School of Mines in the US on the new article.
Flinders University researchers are now testing the tree ‘personality’ system as part of the ‘Drywells and Trees’ project, and investigating how roof water harvesting for garden soils may improve tree health in dry season and enhance canopy cooling in summer.
The project is funded by the Hort Innovation Green Cities Program, together with several city councils including City of Marion, City of Mitcham, City of Unley, City of Port Adelaide Enfield, and City of Onkaparinga. The University of South Australia, Space Down Under, Water Sensitive Urban Design, TreeNet, and Resilient South are also partners in this project.
At the same time, Flinders University experts have recently published a complementary study on vegetation response to climate variability in the Journal of Hydrology, examining better use of water and improved plant evapotranspiration levels to protect urban and other plants in future hotter and drier conditions.
The first article, ‘Enhanced runoff simulation with improved evapotranspiration accounting for vegetation response to climate variability’ (2025) by Nastaran Chitsaz, Margaret Shanafield and Okke Batelaan has been published in the Journal of Hydrology – DOI: 10.1016/j.jhydrol.2025.133988 (published 28 July 2025).
The latest article, ‘Revealing seasonal plasticity of whole-plant hydraulic properties using sap-flow and stem water-potential monitoring’ (2025) by Zhechen Zhang, Huade Guan, Erik Veneklaas, Kamini Singha and Okke Batelaan has been published in Hydrology and Earth System Sciences (European Geosciences Union) DOI: 10.5194/hess-29-3975-2025 (published 28 August 2025).
INDEPENDENT NEWS IS IMPORTANT.
PLEASE GIVE WHAT YOU CAN: PayPal.Me/clevergreensolutions
Enjoy reading Eco Voice? Please help us by purchasing a GIFT Voucher or send one to a friend and encourage people to purchase trees or seeds via The Native Shop – www.nativeshop.com.au
Plants, seeds & more delivered to your door!