Stable carbon isotope composition of terrestrial leaves: inter- and intraspecies variability, cellulose and whole-leaf tissue difference, and potential for climate reconstruction

Stable carbon isotope analysis of terrestrial plant leaves preserved in Quaternary lake sediments has the potential to provide high-resolution reconstructions of past climatic conditions. Preferably, delta(13)C measurements should be made on a single leaf component, e.g. cellulose, but this approach is often precluded by limited leaf availability. Previous work suggests that reliable palaeoclimatic information also may be derived from delta(13)C measurements on whole-leaf tissue, given a similar degree of leaf decomposition between samples. Leaf delta(13)C data for 12 Scandinavian species of dwarf-shrubs, shrubs and trees, and a comparison of delta(13)C data on recent and late Holocene Salix herbacea leaves, revealed that the delta(13)C signal registered by holocellulose is largely reflected by measurements on whole-leaf tissue. Holocellulose was found to be consistently enriched in C-13, although this delta(13)C offset was smaller for subfossil leaves. This supports the use of delta(13)C measurements on whole-leaf tissue for climate reconstruction, at least for leaves preserved in soft, late Holocene sediments with minimal diagenetic effects. Leaf carbon and nitrogen data on fresh leaves of the same 12 Scandinavian species, and corresponding data on late Holocene Salix herbacea leaves, suggest that the leaf C:N ratio is a suitable indicator of the degree of leaf decomposition. Copyright (C) 2003 John Wiley Sons, Ltd.