Carbon, hydrogen and oxygen stable isotope ratios of whole wood, cellulose and lignin methoxyl groups of Picea abies as climate proxies

Abstract

RATIONALE: Carbon, hydrogen and oxygen (C, H and O) stable isotope ratios of whole wood and components are commonly used as paleoclimate proxies. In this work we consider eight different proxies in order to discover the most suitable wood component and stable isotope ratio to provide the strongest climate signal in Picea abies in a southeastern Alpine region (Trentino, Italy). METHODS: d 13 C, d 18 O and d 2 H values in whole wood and cellulose, and d 13 C and d 2 H values in lignin methoxyl groups were measured. Analysis was performed using an Isotopic Ratio Mass Spectrometer coupled with an Elemental Analyser for measuring 13 C/ 12 C and a Pyrolyser for measuring 2 H/ 1 H and 18 O/ 16 O. The data were evaluated by Principal Component Analysis, and a simple Pearson's correlation between isotope chronologies and climatic features, and multiple linear regression were performed to evaluate the data. RESULTS: Each stable isotope ratio in cellulose and lignin methoxyl differs significantly from the same stable isotope ratio in whole wood, the values begin higher in cellulose and lignin except for the lignin d 2 H values. Significant correlations were found between the whole wood and the cellulose fractions for each isotope ratio. Overall, the highest correlations with temperature were found with the d 18 O and d 2 H values in whole wood, whereas no significant correlations were found between isotope proxies and precipitation. CONCLUSIONS: d 18 O and d 2 H values in whole wood provide the best temperature signals in Picea abies in the northern Italian study area. Extraction of cellulose and lignin and analysis of other isotopic ratios do not seem to be necessary.The ANOVA shows the p values between the selected models (Model W for Cermis and Val Maggiore, Model WL for Baselga).

A remarkable relationship of the stable carbon isotopic compositions of wood and cellulose in tree-rings of the tropical species Cariniana micrantha (Ducke) from Brazil

“…Many investigators report very high correlations for the carbon isotopes of total wood and cellulose (Livingston and Spittlehouse, 1996;Borella et al, 1998;Zimmermann, 1998;Dietz, 2006;Gori et al, 2013). In these cases it would make sense to discard the cellulose extraction and restrict the carbon isotope investigations to total wood.…”

“…Craig, 1954;Farmer and Baxter, 1974;Libby et al, 1976). However, with the observation that total wood and cellulose and in general the various wood components differ in their isotopic composition (Wilson and Grinstead, 1977;Yildiz, 1995;Borella et al, 1998;Zimmermann, 1998;Loader et al, 2003;Harlow et al, 2006;Szymczak et al, 2011;Gori et al, 2013), most investigators started to extract cellulose for the purpose of climate reconstruction. The main argument was, to prevent any distortion of the isotopic records due to changing proportions of the different wood components relative to each other.…”

Multi-factorialin vivostable isotope fractionation: causes, correlations, consequences and applications

“…However, we should not forget the importance and the potential of the 'dual-isotope approach' ( [233][234][235], see Section 2.1.6). Finally, completion of the classical tree ring investigation has attained, by δ 2 H and δ 13 C analysis of plant methoxyl groups [14,167], the status of an excellent example for the potential of the multi-element and multi-compound isotope ratio determination providing a maximum of information [246].…”

D/H ratios of methoxyl groups of the sedimentary organic matter of Lake Holzmaar (Eifel, Germany): A potential palaeoclimate/-hydrology proxy

“…Ideally, dD methoxyl values are measured for a particular plant type, for example wood (Keppler et al, 2007;Gori et al, 2013;Feakins et al, 2013a), fruit (Greule and Keppler, 2011) and vegetable species (Keppler and Hamilton, 2008). This thus ensures that the fractionations between dD source and dD methoxyl of each specific plant type is known (Greule and Keppler, 2011).…”

“…dD values of methoxyl groups (dD methoxyl ) have recently been proposed as a potential palaeoclimate proxy (Keppler et al, 2007;Greule and Keppler, 2011;Gori et al, 2013;Feakins et al, 2013a). Methoxyl groups in plant material are either ether bonded, for example in lignin, or, ester bonded, for example in pectin.…”