In a recent Ecohydrology article, Dr Melanie Zeppel has reported the remarkable finding that all Eucalypts measured across Australia used the same amount of water for a given amount of leaf material.
Using native Australian eucalypts, scientists have found a way to calculate how much water forests use across very large scales, a finding that will help Australia manage water resources. There has been increasing demand for scarce water resources, with passionate debate over water allocation, irrigation and extraction in the Murray-Darling Basin. Recently, with more intense floods droughts and heat waves, careful management of water is even more important. At the same time, planting trees is suggested to remove carbon from the atmosphere; however planting trees will use water. So, knowing how much water trees use will help us manage Australia’s variable water resources.
This finding has significant implications for calculating how much water is used in forests across the entire continent. Recent advances in satellite images taken from space mean we can estimate the amount of plant cover at a given location, in a forest, woodland or savanna. Satellite images of leaves can help estimate how much water the entire forest, catchment or even continent uses. “The Eucalyptus has quite remarkable leaf properties, using similar amounts of water, and this simply depends on how many leaves they have”. “These findings on Eucalypts, together with satellite estimates, will allow us to calculate how much water forests use across very large scales” reports Dr Zeppel.
Twenty-one species of Eucalyptus, spanning a 100-fold range in size, from across the continent were analyzed, together with other types of plants such as Callitris, a native pine, and Acacias . The other species used different amounts of water, but remarkably, all the Eucalypts studied used the same amount of water for a given amount of leaves. “Given the ecological and economic importance of forests, these findings are crucial for balancing the water needed to sustain forests with other critical needs” says Jim Lewis, from Fordham University, New York.
Related work published in Nature this year by Australian and US researchers used remotely sensed estimates of plants to estimate water use efficiency across a wide range of Australian and North American landscapes. Plants were able to use water more efficiently than otherwise expected. Professor Huete, from UTS, reports ‘Whereas our work focused on cross-ecosystem convergence in water use, we know that drought coping strategies vary across types of plants, and therefore the results of Dr Zeppel will greatly advance our understanding of how different types of vegetation adapt to drought and avoid mortality.”
The study was inspired by research from Oregon State University, who found ‘universal patterns’ in plants from tropical rainforests. These ‘universal patterns’ tell us if trees of the same size, from different species, have similar water use. These patterns provide powerful tools for transferring results from one site across a much wider spatial scale. Dr Zeppel’s work tested whether these patterns were found in Australia’s plants and was recently published in the journal Ecohydrology.
Dr Zeppel is funded by a Discovery Early Career Researcher Grant, from the Australian Research Council, which is designed to support early career researchers within Australia.
Article: Convergence of tree water use and hydraulic architecture in water-limited regions: a review and synthesis, Ecohydrology: http://onlinelibrary.wiley.
Dr Melanie Zeppel, Department of Biological Sciences, Macquarie University
