Approaches to plant hydrogen and oxygen isoscapes generation

Abstract

Our understanding of the δ2H and δ18O of plant water and tissues ranges from model descriptions of multiple fractionating processes and mechanistic drivers, to primarily observational relationships often described by simple regression relationships. Plant hydrogen and oxygen isoscapes are therefore produced with a range of model sophistications and demonstrate some of the diversity of approaches to producing and utilizing isoscapes in general. Leaf water is central to much of plant H & O isoscape modeling. It affects the atmosphere at large scales by influencing atmospheric CO2 and O2 δ18O, and the biosphere at a range of scales through its influence on the isotopic composition of plant organic compounds. Leaf water isoscapes have therefore been produced as part of efforts to understand atmospheric gas isotopic composition and also have the potential to contribute to other areas where spatial variation in plant-derived organic compound isotope ratios is of interest. For example, improving our understanding of the isotope ratios of cellulose or n-alkanes improves their utility for paleoreconstructions. Spatially-explicit models of food isotope ratios may improve the use of animal isotope ratios to infer migration patterns. Finally, plant hydrogen and oxygen isoscapes can yield forensic information for a variety of products, including food, drugs, or other plant-derived materials. Given this wide range of applications, we discuss approaches to producing plant H & O isoscapes that vary in their complexity depending on the level of mechanistic understanding, data availability, and the question being pursued. © 2010 Springer Science+Business Media B.V.