Abundance and distribution of leaf wax n-alkanes in leaves of Acacia and Eucalyptus trees along a strong humidity gradient in northern Australia |
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| Institution: | 1. DFG-Leibniz Center for Surface Process and Climate Studies, Institute of Earth and Environmental Sciences, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany;2. Institute of Agricultural Sciences, ETH Zurich, Switzerland;3. School of Marine and Tropical Biology, James Cook University, Cairns, Australia;4. Department of Forest and Ecosystem Science, The University of Melbourne, Australia;1. DFG-Leibniz Center for Surface Process and Climate Studies, Institut für Erd- und Umweltwissenschaften, Universität Potsdam, Germany;2. MARUM-Center for Marine Environmental Sciences, Universität Bremen, Germany;3. Max-Planck-Institut für Biogeochemie, Jena, Germany;4. INRA, UR546 BioSP, Avignon, France;5. CEREGE, UMR 7730 Aix-Marseille Université, CNRS, CDF, IRD, Aix-en-Provence, France;6. Faculté des Sciences, Université de Maroua, Cameroon;7. National Herbarium of Cameroon, IRAD, Yaoundé, Cameroon;1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;1. Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Germany;2. Leibniz Institute for Baltic Sea Research, Warnemünde (IOW), Germany;1. Max-Planck-Institut für Biogeochemie, Jena, Germany;2. DFG-Leibniz Center for Surface Process and Climate Studies, Institut für Erd- und Umweltwissenschaften, Universität Potsdam, Germany;3. Faculté des Sciences, University of Maroua, Cameroon;4. National Herbarium of Cameroon, IRAD, Yaoundé, Cameroon |
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| Abstract: | Environmental parameters such as rainfall, temperature and relative humidity can affect the composition of higher plant leaf wax. The abundance and distribution of leaf wax biomarkers, such as long chain n-alkanes, in sedimentary archives have therefore been proposed as proxies reflecting climate change. However, a robust palaeoclimatic interpretation requires a thorough understanding of how environmental changes affect leaf wax n-alkane distributions in living plants. We have analysed the concentration and chain length distribution of leaf wax n-alkanes in Acacia and Eucalyptus species along a 1500 km climatic gradient in northern Australia that ranges from subtropical to arid. We show that aridity affected the concentration and distribution of n-alkanes for plants in both genera. For both Acacia and Eucalyptus n-alkane concentration increased by a factor of ten to the dry centre of Australia, reflecting the purpose of the wax in preventing water loss from the leaf. Furthermore, Acacian-alkanes decreased in average chain length (ACL) towards the arid centre of Australia, whereas Eucalyptus ACL increased under arid conditions. Our observations demonstrate that n-alkane concentration and distribution in leaf wax are sensitive to hydroclimatic conditions. These parameters could therefore potentially be employed in palaeorecords to estimate past environmental change. However, our finding of a distinct response of n-alkane ACL values to hydrological changes in different taxa also implies that the often assumed increase in ACL under drier conditions is not a robust feature for all plant species and genera and as such additional information about the prevalent vegetation are required when ACL values are used as a palaeoclimate proxy. |
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