Hydrogen isotope fractionation in carbohydrates of leaves and xylem tissues follows distinct phylogenetic patterns: a common garden experiment with 73 tree and shrub species

center dot Recent methodological advancements in determining the nonexchangeable hydrogen isotopic composition (delta H-2(ne)) of plant carbohydrates make it possible to disentangle the drivers of hydrogen isotope (H-2) fractionation processes in plants. center dot Here, we investigated the influence of phylogeny on the delta H-2(ne) of twig xylem cellulose and xylem water, as well as leaf sugars and leaf water, across 73 Northern Hemisphere tree and shrub species growing in a common garden. center dot H-2 fractionation in plant carbohydrates followed distinct phylogenetic patterns, with phylogeny reflected more in the delta H-2(ne) of leaf sugars than in that of twig xylem cellulose. Phylogeny had no detectable influence on the delta H-2(ne) of twig or leaf water, showing that biochemistry, not isotopic differences in plant water, caused the observed phylogenetic pattern in carbohydrates. Angiosperms were more H-2-enriched than gymnosperms, but substantial delta H-2(ne) variations also occurred at the order, family, and species levels within both clades. Differences in the strength of the phylogenetic signals in d2Hne of leaf sugars and twig xylem cellulose suggest that the original phylogenetic signal of autotrophic processes was altered by subsequent species-specific metabolism. center dot Our results will help improve H-2 fractionation models for plant carbohydrates and have important consequences for dendrochronological and ecophysiological studies.

Automated summary

Recent methodological advancements have allowed us to determine the nonexchangeable hydrogen isotopic composition of plant carbohydrates, providing insights into the drivers of hydrogen isotope fractionation processes in plants. In our study, we examined the influence of phylogeny on the isotopic composition of various plant tissues, and found that phylogeny plays a role in hydrogen isotope fractionation in plant carbohydrates, particularly in leaf sugars. Our findings also suggest that the original phylogenetic signal of autotrophic processes is modified by species-specific metabolism. These results have important implications for dendrochronological and ecophysiological studies and can improve hydrogen isotope fractionation models for plant carbohydrates.