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| Titel |
Explanations for the unexplained variance of oxygen isotope ratios in tree rings |
| VerfasserIn |
M. Saurer, A. Kress, O. Sidorova, R. Siegwolf |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025092
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| Zusammenfassung |
| Correlations between oxygen isotope ratios of tree-rings and temperature are sometimes
weaker than expected and often lower than the respective correlations with carbon isotope
ratios. This observation could be caused by biological fractionation effects and evaporation in
the soil and plant, leading to changes in the isotope ratio that depend on local ecological
factors and tree species. However, δ18O tree-ring chronologies from different sites often show
a strong common signal, as recently observed for several temperate sites in Switzerland. This
indicates a common driving force for the oxygen isotope changes, although simple
correlations to temperature or precipitation still do not explain a very high amount of the
variance. One explanation could be that the “input” oxygen isotope signal for the tree, namely
the isotope signal of precipitation and soil water, is also not a simple measure of temperature
if the year-to-year variability of summer values is considered. In this study, we (1)
compared tree-ring chronologies not only to simple climate parameters like temperature,
but also investigated the influence of atmospheric circulation patterns to extract
possibly hidden climatic information, and we (2) investigated δ18O variations from
different species growing at the same site to assess the influence of biological effects. |
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