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

- The carbon isotopes of total wood and its cellulose from 253 tree-rings of Cariniana micranta (Ducke) were investigated.
- The correlation for the whole time period was very high (r = 0.96) but striking deviations are found for different sub-periods.
- During intervals of low isotopic variability, changing proportions of wood components may lead to different isotopic patterns.
- High correlation from a subset of a longer isotopic record cannot necessarily prove its validity for the whole record.
- Analysis of wood is adequate for long term trends while for short term aspects cellulose may provide different information.

The stable isotopes of carbon were analysed in total wood and cellulose from the tree-rings of the tropical wood species Cariniana micrantha (Ducke). The aim was to examine the isotopic relationship between total wood and its cellulose over the last two and a half centuries. Although the correlation for the whole time period is very high (r = 0.96) it is remarkable that different sub-periods deviate strongly from this close relationship. Consequently, a good correlation from the subset of a longer isotopic record cannot necessarily prove its validity for the whole record. The study indicates that changes of the carbon isotopes of cellulose and of total wood show sometimes during short sub-periods different isotope patterns presumably caused by different environmental effects. Thorough calculations indicate that strong variations within the isotopic record especially changes of the isotopic level along a chronology lead to high correlations between δ13Cwood and δ13Ccel. Contrary thereto subsections with low isotopic variability lead to low correlations. The results imply that long term trends provide similar patterns. Therefore, if long term trends are of interest such as e.g. in climate reconstruction then total wood can be analysed in favour of cellulose, thus saving a tremendous amount of work. However, if short term aspects from a longer record are of interest, cellulose and total wood may sometimes provide different information. In addition it is hypothesized that during intervals of low isotopic variability the proportions of the various wood components may change relative to each other, leading for certain time intervals to different isotope patterns.