@article{KleyerSchroederEsselbachBiedermannetal.2004,
  author    = {Kleyer, Michael and Schr{\"o}der-Esselbach, Boris and Biedermann, Robert and Rudner, Michael and Fritzsch, K. and K{\"u}hner, A. and Poschlod, P. and Kahmen, S. and Tackenberg, O. and Talmon, E. and Poethke, H.-J. and Obermaier, E. and Hein, S. and Hinsch, M. and Henle, K. and Settele, Josef and Binzenh{\"o}fer, Birgit and Pfeifer, A. and K{\"o}gl, H.},
  title     = {Freie Beweidung mit geringer Besatzdichte und Fr{\"a}sen als alternative Verfahren zur Pflege von Magerrasen},
  issn      = {0341-7026},
  year      = {2004},
  language  = {de}
}
@article{RachEngelsKahmenetal.2017,
  author    = {Rach, Oliver and Engels, S. and Kahmen, A. and Brauer, Achim and Martin-Puertas, C. and van Geel, B. and Sachse, Dirk},
  title     = {Hydrological and ecological changes in western Europe between 3200 and 2000 years BP derived from lipid biomarker delta D values in lake Meerfelder Maar sediments},
  series = {Quaternary science reviews : the international multidisciplinary research and review journal},
  volume    = {172},
  journal   = {Quaternary science reviews : the international multidisciplinary research and review journal},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0277-3791},
  doi       = {10.1016/j.quascirev.2017.07.019},
  pages     = {44 -- 54},
  year      = {2017},
  abstract  = {One of the most significant Late Holocene climate shifts occurred around 2800 years ago, when cooler and wetter climate conditions established in western Europe. This shift coincided with an abrupt change in regional atmospheric circulation between 2760 and 2560 cal years BP, which has been linked to a grand solar minimum with the same duration (the Homeric Minimum). We investigated the temporal sequence of hydroclimatic and vegetation changes across this interval of climatic change (Homeric climate oscillation) by using lipid biomarker stable hydrogen isotope ratios (ED values) and pollen assemblages from the annually-laminated sediment record from lake Meerfelder Maar (Germany). Over the investigated interval (3200-2000 varve years BP), terrestrial lipid biomarker ED showed a gradual trend to more negative values, consistent with the western Europe long-term climate trend of the Late Holocene. At ca. 2640 varve years BP we identified a strong increase in aquatic plants and algal remains, indicating a rapid change in the aquatic ecosystem superimposed on this long-term trend. Interestingly, this aquatic ecosystem change was accompanied by large changes in ED values of aquatic lipid biomarkers, such as nC(21) and nC(23) (by between 22 and 30\%(0)). As these variations cannot solely be explained by hydroclimate changes, we suggest that these changes in the Wag value were influenced by changes in n-alkane source organisms. Our results illustrate that if ubiquitous aquatic lipid biomarkers are derived from a limited pool of organisms, changes in lake ecology can be a driving factor for variations on sedimentary lipid MN values, which then could be easily misinterpreted in terms of hydro climatic changes. (C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{HoffmannKahmenCernusaketal.2013,
  author    = {Hoffmann, Bernd and Kahmen, Ansgar and Cernusak, Lucas A. and Arndt, Stefan K. and Sachse, Dirk},
  title     = {Abundance and distribution of leaf wax n-alkanes in leaves of Acacia and Eucalyptus trees along a strong humidity gradient in northern Australia},
  series = {Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry},
  volume    = {62},
  journal   = {Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry},
  number    = {9},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0146-6380},
  doi       = {10.1016/j.orggeochem.2013.07.003},
  pages     = {62 -- 67},
  year      = {2013},
  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.},
  language  = {en}
}
@misc{SachseBillaultBowenetal.2012,
  author    = {Sachse, Dirk and Billault, Isabelle and Bowen, Gabriel J. and Chikaraishi, Yoshito and Dawson, Todd E. and Feakins, Sarah J. and Freeman, Katherine H. and Magill, Clayton R. and McInerney, Francesca A. and van der Meer, Marcel T. J. and Polissar, Pratigya and Robins, Richard J. and Sachs, Julian P. and Schmidt, Hanns-Ludwig and Sessions, Alex L. and White, James W. C. and West, Jason B. and Kahmen, Ansgar},
  title     = {Molecular Paleohydrology interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms},
  series = {Annual review of earth and planetary sciences},
  volume    = {40},
  journal   = {Annual review of earth and planetary sciences},
  number    = {1},
  editor    = {Jeanloz, R},
  publisher = {Annual Reviews},
  address   = {Palo Alto},
  isbn      = {978-0-8243-2040-9},
  issn      = {0084-6597},
  doi       = {10.1146/annurev-earth-042711-105535},
  pages     = {221 -- 249},
  year      = {2012},
  abstract  = {Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have been increasingly used as paleohydrological proxies over a range of geological timescales. Isotopic fractionation observed between hydrogen in environmental water and hydrogen in lipids, however, is sensitive to biochemical, physiological, and environmental influences on the composition of hydrogen available for biosynthesis in cells. Here we review the factors and processes that are known to influence the hydrogen-isotopic compositions of lipids-especially n-alkanes-from photosynthesizing organisms, and we provide a framework for interpreting their D/H ratios from ancient sediments and identify future research opportunities.},
  language  = {en}
}
@article{GamarraSachseKahmen2016,
  author    = {Gamarra, B. and Sachse, Dirk and Kahmen, A.},
  title     = {Effects of leaf water evaporative H-2-enrichment and biosynthetic fractionation on leaf wax n-alkane H-2 values in C3 and C4 grasses},
  series = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology},
  volume    = {39},
  journal   = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0140-7791},
  doi       = {10.1111/pce.12789},
  pages     = {2390 -- 2403},
  year      = {2016},
  abstract  = {Leaf wax n-alkane H-2 values carry important information about environmental and ecophysiological processes in plants. However, the physiological and biochemical drivers that shape leaf wax n-alkane H-2 values are not completely understood. It is particularly unclear why n-alkanes in grasses are typically H-2-depleted compared with plants from other taxonomic groups such as dicotyledonous plants and why C3 grasses are H-2-depleted compared with C4 grasses. To resolve these uncertainties, we quantified the effects of leaf water evaporative H-2-enrichment and biosynthetic hydrogen isotope fractionation on n-alkane H-2 values for a range of C3 and C4 grasses grown in climate-controlled chambers. We found that only a fraction of leaf water evaporative H-2-enrichment is imprinted on the leaf wax n-alkane H-2 values in grasses. This is interesting, as previous studies have shown in dicotyledonous plants a nearly complete transfer of this H-2-enrichment to the n-alkane H-2 values. We thus infer that the typically observed H-2-depletion of n-alkanes in grasses (as opposed to dicots) is because only a fraction of the leaf water evaporative H-2-enrichment is imprinted on the H-2 values. Our experiments also show that differences in n-alkane H-2 values between C3 and C4 grasses are largely the result of systematic differences in biosynthetic fractionation between these two plant groups, which was on average -198 and-159 parts per thousand for C3 and C4 grasses, respectively. We present novel and exciting data on how leaf wax n-alkane 2H values from grasses are affected by plant physiological (leaf water evaporative 2H-enrichment) or biochemical processes (biosynthetic hydrogen isotope fractionation). These results are very interesting because they shed new light on how naturally observed differences between 2H values from C3 and C4 grasses and dicots can be explained by systematic differences in the biosynthesis of n-alkanes between these plant group (i.e. largely driven by NADPH origins).},
  language  = {en}
}