Leaf water deuterium enrichment shapes leaf wax n-alkane δD values of angiosperm plants II: observational evidence and global implications

Kahmen, Ansgar, Hoffmann, Bernd, Schefuβ, Enno, Arndt, Stefan K., Cernusak, Lucas A., West, Jason B., and Sachse, Dirk (2013) Leaf water deuterium enrichment shapes leaf wax n-alkane δD values of angiosperm plants II: observational evidence and global implications. Geochimica et Cosmochimica Acta, 111. pp. 50-63.

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Abstract

Leaf wax n-alkanes are long-chain hydrocarbons that can persist in sedimentary records over geological timescales. Since their hydrogen isotopic composition (expressed as a δD value) can be correlated to the δD values of precipitation, leaf wax n-alkane δD values have been advocated as new and powerful proxies for paleohydrological research. The exact type of hydrological information that is recorded in the δD values of leaf wax n-alkanes remains, however, unclear. In a companion paper we provide experimental evidence showing that the δD values of leaf wax n-alkanes of angiosperm plants grown under controlled environmental conditions not only reflect δD values of precipitation – as has often been assumed – but that evaporative deuterium (D)-enrichment of leaf water has an additional critical effect on their δD values. Here we present a detailed observational study that illustrates that evaporative D-enrichment of leaf water also affects the δD values of leaf wax n-alkanes in plants from natural ecosystems along a 1500 km climate gradient in Northern Australia. Based on global simulations of leaf water D-enrichment we show that the effects of evaporative D-enrichment of leaf water on leaf wax n-alkane δD values is relevant in all biomes but that it is particularly important in arid environments. Given the combined influence of precipitation δD values and leaf water D-enrichment we argue that leaf wax n-alkane δD values contain an integrated signal that can provide general hydrological information, e.g. on the aridity of a catchment area. We also suggest that more specific hydrological information and even plant physiological information can be obtained from leaf wax n-alkanes if additional indicators are available to constrain the plant- and precipitation-derived influences on their δD values. As such, our findings have important implications for the interpretation of leaf wax n-alkane δD values from paleohydrological records. In addition, our investigations open the door to employ δD values of leaf wax n-alkanes as new ecohydrological proxies in contemporary plant and ecosystem sciences.

Item ID: 30128
Item Type: Article (Refereed Research - C1)
ISSN: 1872-9533
Funders: ERC Starting Grant, German Science Foundation, Australian Research Council (ARC), Charles Darwin University
Projects and Grants: ERC Starting grant 279518 COSIWAX, German Science Foundation Emmy-Noether Research grant DFG SA-1889/1-1, German Science Foundation grant DFG SCHE-903/8, ARC Discovery grant DP0771427, ARC Future Fellowship grant FT100100329
Date Deposited: 08 Nov 2013 06:11
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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