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| Titel |
Long-term trends in C, O, and N isotopes in tree rings from pristine tropical forests |
| VerfasserIn |
P. Hietz, O. Dünisch, C. Nock, A. Leis, W. Wanek |
| 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 |
250027823
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| Zusammenfassung |
| Various drivers of global change can affect tree growth and forest dynamics, but these effects are poorly known for tropical forests. By analysing trees of different ages and wood of different cambial age from trees in pristine tropical forests in Brazil and Thailand, we distinguish between long-term changes (decadal) related to the environment and changes related to the trees’ ontogeny (cambial age). Cellulose 13C trends were independent of tree age, reflecting the rise in CO2 concentration that result in increases in tree water use efficiency. By contrast, cellulose 18O showed no long-term trend, but increased with tree age in some species, which may be caused if larger trees access water from different soil layers or the crown grows to higher canopy strata. 15N significantly declined with cambial age, which may reflect different nitrogen sources or internal recycling in larger trees, or soil development in microsites where trees regenerate. However, independent of tree age, there were also long-term changes in 15N that point to changes in the N cycle even in tropical forests that are rather remote from N emissions. Whether these are related to increased N input or indirect effects of CO2 on the N cycle, remains unknown. |
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