Recently I have been involved in an ARC Linkage project investigating sap flow and stem water storage by Eucalypts in the Cotter Catchment, ACT, Australia. The Cotter is an important subalpine water catchment providing water to Canberra. To understand how environmental conditions influence catchment water yield, we have installed sap flow probes in stems of various sizes in the catchment to assess how water is used by trees in this region relative to the water available from the substrate. The sap flow probes we are using have been developed and built by ourselves. As with the other sensors I have helped to develop, the probes are low cost, compared to commercially available devices, so can be manufactured in large quantities and be installed in stems long term, logging continuously over time.
Runoff from high country forests dominates water supply for cities and agriculture in southeastern Australia, but our ability to predict effects of environmental stress and change on catchment water yield is poor. Two important reasons for this are that (i) we lack a thorough understanding of how tree water loss responds to drought and other factors, and (ii) it is difficult to study and quantify tree water loss reliably because of limitations to sap flow methodologies and because the dynamics of transpiration are decoupled from those of stem water flow by stem water storage. The objective of this project is to develop and test new methods to measure sap flow and stem water storage concurrently, and to use these methods in conjunction with measurements of soil water storage to parameterize a mechanistic model of transpiration and subsurface hydrology in an important subalpine water catchment. This project is funded by the Australian Research Council Linkage Project 130101183. T. N. Buckley, 2017
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