Reducing uncertainties in δ¹³C analysis of tree rings: Pooling, milling, and cellulose extraction

Abstract

Abstract. Recent developments of on-line methods have provided another boost to the determination of stable isotope ratios in organic material. Along with a significant increase in sample throughput, the sample sizes decrease, both of which are necessary conditions to acquire long time series from limited wood amounts. In view of this new technique we reconsidered the most important factors influencing the measured isotopic signature which are (1) pooling, (2) homogeneity, and (3) cellulose extraction. In most cases, pooling (i.e., mixing wood of the same year from different trees) can be made in a simple way by mixing the whole wood available because mass-weighted and unweighted isotope measurements were the same within the error. More attention must be paid in homogenizing the sample. Theoretical considerations underpinned by experimental results suggest a fineness of 0.15 mm (115 mesh) if cellulose is extracted and 0.1 mm (165 mesh) for direct wood analysis. Many of previous studies did not achieve this fineness. We find that wood is as good a climate proxy as cellulose. This is shown by comparing correlations of wood and corresponding cellulose isotope values with meteorological data, which are identical within the uncertainty.

Annual cyclicity in high‐resolution stable carbon and oxygen isotope ratios in the wood of the mangrove tree Rhizophora mucronata

“…This has been reported for stable carbon isotope ratios analysed with annual resolution (Livingston & Spittlehouse 1996;Borella et al 1998;MacFarlane et al 1999) and with ultra-high resolution (Helle & Schleser 2004a). In addition, Loader, Robertson & McCarroll (2003) found that bulk wood is a better climate proxy than a-cellulose.…”

Multiple tree-ring proxies (earlywood width, latewood width and δ13C) from pedunculate oak (Quercus robur L.), Hungary

“…Therefore, to ensure the annual resolution of the environmental record, only latewood was analysed in this study. The measurements were carried out on wood since 13 C/ 12 C ratios determined in bulk wood showed the same relative variations as in isolated cellulose (Leavitt and Long, 1982;Borella et al, 1998;Loader et al, 2003) and moreover stronger climate response was found for bulk wood compared to cellulose, especially for pedunculate oak, without any temporal offset in the climate response (Loader et al, 2003). Wood slivers (~1-5 mg) were combusted in a Pyrex tube with CuO (Boutton et al, 1983).…”

Productivity, carbon isotope discrimination and leaf traits of trees of Eucalyptus globulus Labill. in relation to water availability

“…However, strong correlations between D of whole tissue and cellulose have led others to conclude that whole wood provides a good 'climate proxy' (e.g. Borella et al 1998) and whole wood and leaf tissue were used for subsequent analyses in this study. The 13 C/ 12 C ratio (d 13 C) of a 2-mg subsample of whole wood, whole leaf or leaf holocellulose material was determined as described in Macfarlane & Adams (1998).…”