International team tests measurement of stress in trees

Published 01 September 2009

kathyAn international team of scientists working at the University of New England has been experimenting with technologies that can help to monitor the health of the environment by measuring the level of “stress” in trees.

Professor Kathy Steppe (pictured here) and Dr Dirk De Pauw travelled from Belgium to spend the past month in Armidale working with UNE plant ecophysiologist Dr Nigel Warwick and Alec Downey from ICT International, an Armidale-based company making – and distributing world-wide – equipment for plant, soil, and environmental monitoring. Professor Steppe comes from the Laboratory of Plant Ecology at Ghent University, and Dr De Pauw is Chief Executive Officer of Phyto-IT, Belgium – a  company that specialises in the analysis of data from – and the mathematical modelling of – plant systems.

They have been conducting experiments to compare the performance of three technologies that all use a pulse of heat injected into a tree trunk to measure how fast the sap is travelling up the trunk. As the heat pulse travels with the sap, sensors in the trunk measure its progress. The rate of flow is a sensitive indicator of the degree of environmental stress.

“Our original sap flow measurements were done on European trees in the Northern Hemisphere,” said Professor Steppe, “and in coming to Armidale we’ve had a chance to measure sap flow in eucalypts and acacias.” The research visit of Professor Steppe was funded by a grant from the National Fund for Scientific Research, Belgium (FWO).

“Our job here is to compare three different ways of measuring the movement of the heat pulse, and to assess the accuracy of the sensors and the effectiveness of these systems in measuring stress in trees,” said Dr De Pauw, who designs software for analysing the data recorded by the heat-pulse instruments.

In the experiments at UNE the scientists were able to control and vary the rate at which water flowed through sections of tree trunk, and see how accurately the three different measurement systems recorded these varying rates of flow. Dr Warwick pointed out that, after the development of semiconductor technology in the 1990s, accurate measurements were now possible. “But we still don’t know the biology,” he said, “- for example, how wood behaves when it’s heated. Now that we have accurate instruments we can start asking some really interesting questions.”

Mr Downey, who is the Manager of Plant Science Applications and Research at ICT International, said that his Armidale-based company exported monitoring equipment to countries on all continents. “The company’s owned and operated by scientists for scientists,” he said.

He explained the role of equipment such as heat-pulse sensors in the large-scale modelling of environmental phenomena such as carbon sequestration. “The more water that flows through a tree, the more carbon it can store,” he said.

Dr Warwick said that UNE’s collaboration with Northern-Hemisphere scientists and an Armidale-based company that supplied monitoring equipment to the world gave the current experiments a uniquely global perspective.

THE PHOTOGRAPH of Professor Kathy Steppe displayed here expands to show her working with (from left) Dr Dirk De Pauw, Dr Nigel Warwick, and Alec Downey.