Expressing leaf water and cellulose oxygen isotope ratios as enrichment above source water reveals evidence of a Péclet effect

摘要

There is an increasing ecological interest in understanding the gradients in H2 18O enrichment in leaf water (i.e. a Péclet effect), because an appreciation of the significance of the Péclet effect is important for improving our understanding of the mechanistic processes affecting the 18O composition of leaf water and plant organic material. In data sets where both source water and leaf water 18O data are available, we can evaluate the potential contribution of a Péclet effect. As an example, we recalculate data published earlier by Roden and Ehleringer (1999, Oecologia 121:467–477) as enrichments in leaf water (ΔL) and cellulose (Δcell) above source water. Based on these recalculations, we present support for the relevance of a Péclet effect in leaves. Further, we demonstrate that the subtle variations in ΔL and Δcell caused by a Péclet effect may be masked in experimental systems in which variation in the source water oxygen isotope ratio is considerable.