Carbon uptake and water use in woodlands and forests in southern Australia during an extreme heat wave event in the “Angry Summer” of 2012/2013
[2];
[3];
[4];
[6];
[7];
[10];
[12];
[16];
[17]
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Yarralumla, NSW (Australia). Oceans and Atmosphere
- ETH Zurich (Switzerland)
- Univ. of Technology, Sydney, NSW (Australia)
- Flinders Univ., Salisbury South, SA (Australia). Airborne Research Australia
- The Univ. of Melbourne, Richmond, VIC (Australia)
- The Univ. of Western Australia, Crawley, WA (Australia)
- Univ. of Lleida (Spain). Agotecnio-Center, Dept. of Plant Production and Forest Science
- The Univ. of Sydney, NSW (Australia)
- The Univ. of Melbourne, Richmond, VIC (Australia); Western Sydney Univ., Penrith, NSW (Australia). Hawkesbury Inst. for the Environment
- Charles Darwin Univ., NT (Australia). Research Inst. for the Environment and Livelihoods
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Swansea Univ., Singleton Park, Swansea (United Kingdom)
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Floreat, WA (Australia). Land and Water
- The Univ. of Adelaide, SA (Australia). Environment Inst.
- Monash Univ., Clayton, VIC (Australia)
- Western Sydney Univ., Penrith, NSW (Australia). Hawkesbury Inst. for the Environment
- Edith Cowan Univ., Joondalup, WA (Australia). Centre for Ecosystem Management
As 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 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.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); Australian Terrestrial Ecosystem Research Network (TERN); Australian Research Council (ARC); Australia Department of the Environment and Energy; European Commission (EC); The Royal Society
- Grant/Contract Number:
- AC02-05CH11231; 300083; RYC-2012-10970; IE110132
- OSTI ID:
- 1581689
- Journal Information:
- Biogeosciences (Online), Vol. 13, Issue 21; ISSN 1726-4189
- Publisher:
- European Geosciences UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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