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dc.contributor.authorvan Gorsel, Eva
dc.contributor.authorWolf, Sebastian
dc.contributor.authorJames Cleverly, James
dc.contributor.authorIsaac, Peter
dc.contributor.authorHaverd, Vanessa
dc.contributor.authorEwenz, Cacilia
dc.contributor.authorArndt, Stefan K.
dc.contributor.authorBeringer, Jason
dc.contributor.authorResco de Dios, Víctor
dc.contributor.authorEvans, Bradley
dc.contributor.authorGriebel, Anne
dc.contributor.authorHutley, Lindsay B.
dc.contributor.authorKeenan, Trevor
dc.contributor.authorKljun, Natascha
dc.contributor.authorMacfarlane, Craig
dc.contributor.authorMeyer, Wayne S.
dc.contributor.authorMcHugh, Ian
dc.contributor.authorPendall, Elise
dc.contributor.authorProber, Suzanne M.
dc.contributor.authorSilberstein, Richard
dc.description.abstractAs a result of climate change warmer temperatures are projected through the 21st century and are already increasing above modelled predictions. Apart from increases in the mean, warm/hot temperature extremes are expected to become more prevalent in the future, along with an increase in the frequency of droughts. It is crucial to better understand the response of terrestrial ecosystems to such temperature extremes for predicting land-surface feedbacks in a changing climate. While land-surface feedbacks in drought conditions and during heat waves have been reported from Europe and the US, direct observations of the impact of such extremes on the carbon and water cycles in Australia have been lacking. During the 2012/2013 summer, Australia experienced a record-breaking heat wave with an exceptional spatial extent that lasted for several weeks. In this study we synthesised eddy-covariance measurements from seven woodlands and one forest site across three biogeographic regions in southern Australia. These observations were combined with model results from BIOS2 (Haverd et al., 2013a, b) to investigate the effect of the summer heat wave on the carbon and water exchange of terrestrial ecosystems which are known for their resilience toward hot and dry conditions. We found that water-limited woodland and energy-limited forest ecosystems responded differently to the heat wave. During the most intense part of the heat wave, the woodlands experienced decreased latent heat flux (23 % of background value), increased Bowen ratio (154 %) and reduced carbon uptake (60 %). At the same time the forest ecosystem showed increased latent heat flux (151 %), reduced Bowen ratio (19 %) and increased carbon uptake (112 %). Higher temperatures caused increased ecosystem respiration at all sites (up to 139 %). During daytime all ecosystems remained carbon sinks, but carbon uptake was reduced in magnitude. The number of hours during which the ecosystem acted as a carbon sink was also reduced, which switched the woodlands into a carbon source on a daily average. Precipitation occurred after the first, most intense part of the heat wave, and the subsequent cooler temperatures in the temperate woodlands led to recovery of the carbon sink, decreased the Bowen ratio (65 %) and hence increased evaporative cooling. Gross primary productivity in the woodlands recovered quickly with precipitation and cooler temperatures but respiration remained high. While the forest proved relatively resilient to this short-term heat extreme the response of the woodlands is the first direct evidence that the carbon sinks of large areas of Australia may not be sustainable in a future climate with an increased number, intensity and duration of heat waves.ca_ES
dc.description.sponsorshipThis work utilised data from the OzFlux network which is supported by the Australian Terrestrial Ecosystem Research Network (TERN; and by grants funded by the Australian Research Council. We would like to acknowledge the contributions Ray Leuning made to OzFlux and Au-Tum. Ray Leuning has been cofounder and leader of the OzFlux community and has been a great mentor to many in our network. We would also like to acknowledge the strong leadership role that Helen Cleugh had over many years. The network would not be where it is without their input. Víctor Resco de Dios and Elise Pendal acknowledge the Education Investment Fund and HIE for construction and maintenance of the AU-Cum tower. The Australian Climate Change Science Program supported contributions by Eva van Gorsel and Vanessa Haverd, and Sebastian Wolf was supported by the European Commission’s FP7 (Marie Curie International Outgoing Fellowship, grant 300083) and ETH Zurich. Víctor Resco de Dios acknowledges funding from a Ramón y Cajal fellowship RYC-2012-10970. Natascha Kljun acknowledges funding from The Royal Society UK, grant IE110132.We would further like to acknowledge the referees and their helpful comments, which have helped us to improve the manuscript.ca_ES
dc.publisherCopernicus Publicationsca_ES
dc.relation.isformatofReproducció del document publicat a
dc.relation.ispartofBiogeosciences, 2016, vol. 13, núm. 21, p. 5947-5964ca_ES
dc.rightscc-by (c) van Gorsel, Eva. et al., 2016ca_ES
dc.titleCarbon uptake and water use in woodlands and forests in southern Australia during an extreme heat wave event in the “Angry Summer” of 2012/2013ca_ES

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