Effect of continuous light on leaf wax isotope ratios in Betula nana and Eriophorum vaginatum: Implications for Arctic paleoclimate reconstructions

摘要: Abstract Reconstructions of climate using leaf wax D/H ratios (δDwax) require accounting for the apparent isotopic fractionation (eapp) between plant source water and waxes. There have been conflicting publications on whether plants in Arctic growing under 24-hour continuous light, fractionate less than temperate tropical plants. In this study, we examine effect diurnal light (DL) versus (CL) composition n-alkanes n-acids greenhouse experiments two common (Eriophorum vaginatum, or tussock cottongrass Betula nana, dwarf birch). For E. δDwax values various homologues were 5–11‰ more positive CL relative to their DL counterparts, whereas B. waxes 3–24‰ negative, suggesting that daylight length is not a unifying control The δ13Cwax nana was negative grown compared reflecting lower water-use efficiency, associated with prolonged stomatal opening treatment. We modeled impact increasing conductance effective flow path lengths (mimicking variable morphologies) waters (δDlw) find variations leaf-water enrichment may explain responses seen vaginatum nana. suggest between-species differences δDlw response utilization stored carbohydrates, important governing δDwax. Our results do consistently display reduced eapp as result day providing additional support field observations.