Developing a molecular ISOSCAPE for an alpine watershed to mechanistically assess the spatial variability of leaf wax lipid δD values in plants, soils and sediments
Funded by the Swiss National Science Foundation
Duration: 01.01.2014 – 31.12.2016
Responsible Scientists: Dr. Sarah Newberry, Prof. Ansgar Kahmen (PI)
Leaf wax lipids are long-chained hydrocarbons that are vital components of plant cuticles. Leaf wax lipids are abundant in leaves, soils and sediments and can persist in the environment over millions of years. What makes leaf wax lipids unique is that their stable hydrogen isotope composition (δ2H) contains information on precipitation and evapotranspiration. With this exceptional combination of properties, leaf wax lipids and their δ2H values are now being celebrated as the much-needed (eco)hydrological proxies that provide information on the hydrological cycle across new spatial and temporal scales. Little is, however, known on the watershed level variability of leaf wax lipid δ2H values and on the spatial variability of the abiotic (precipitation) and biotic (evapotranspiration) hydrological signals that are recorded in leaf wax lipid δ2H values. Moreover, the integration of the inherent variability of leaf wax lipid δ2H signals that has been observed within and among different plant communities into the soil and sediment record is presently unknown.
The research project will use an experimental watershed in the Swiss Alps as a model system to study the spatial variability of leaf wax lipid δ2H values within and among plant communities, soils and sediments to assess the abiotic and biotic drivers of this variability at the landscape level. The key goal of the project is to establish linkages between the known processes that determine leaf wax lipid δ2H values at the leaf level with 1) the spatial variability of those same processes at the watershed level; and 2) the processes that ultimately integrate that variability in leaf wax lipid δ2H values in the soil and sediment record across the watershed. A particularly novel aspect of the proposed research is the development of the first molecular isoscapes, literally maps of the variation in leaf wax lipid δ2δ2H values from sediment records when these are used as hydrological proxies in paleohydrological applications.