Variation in hydrogen stable isotopes in cellulose and n-alkanes: phylogenetic signal and related traits

Hydrogen (H) stable isotope analysis of specific plant organic compounds has become of interest as a tool for ecological, environmental and palaeoclimatological studies. Aside from the influence of leaf water evaporative enrichment on the δ²H composition of organic compounds, hydrogen isotope fractionation occurs during carbon metabolism in the plant (ε_bio). To get a better understanding of the metabolic signal recorded in ε_bio, we explored the variation of δ²H in cellulose and n-alkanes, and its relationship with phylogeny and other plant traits. Leaf material of a large set of species in the eudicot clade was collected in the botanical garden at the University of Basel, cellulose and n-alkanes were extracted, δ²H in both compounds and δ¹⁸O in cellulose were analysed. It was found that modelled leaf water differences only explain part of the observed variation of δ²H in organic compounds. δ²H appears to be related to phylogeny and a wider assessment of trait data is currently being undertaken to test for signal associations with physiological traits. This study helps address at which taxonomic level the variation of δ²H is found; illuminate plant physiological traits that can be responsible for shaping species specific δ²H values in organic compounds; as well as, provide novel insights into the δ²H covariation between cellulose and n-alkanes.