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| Titel |
Tree ring isotopes of beech and spruce in response to short-term climate variability across Central European sites: Common and contrasting physiological mechanisms |
| VerfasserIn |
Rosemarie Weigt, Stefan Klesse, Kerstin Treydte, David Frank, Matthias Saurer, Rolf T. W. Siegwolf |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250135762
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| Publikation (Nr.) |
 EGU/EGU2016-16667.pdf |
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| Zusammenfassung |
| The combined study of tree-ring width and stable C and O isotopes provides insight in the
coherences between carbon allocation during stem growth and the preceding conditions of
gas exchange and formation of photosynthates as all influenced by environmental
variation.
In this large-scale study comprising 10 sites across a range of climate gradients
(temperature, precipitation) throughout Central Europe, we investigated tree-rings in
European beech (Fagus sylvatica) and Norway spruce (Picea abies) trees. The sampling
design included larger and smaller trees. The short-term, i.e. year-to-year, variability in the
isotope time series over 100 yrs was analyzed in relation to tree-ring growth and climate
variation. The generally strong correlation between the year-to-year differences in
δ13C (corrected for the atmospheric shift due to 13C-depleted CO2 from fossil
combustion) and δ18O across most sites emphasized the role of stomatal conductance in
controlling leaf gas exchange. However, the correlation between both isotopes decreased
during some periods. At several sites this reduction in correlation was particularly
pronounced during recent decades. This suggests a decoupling between stomatal
and photosynthetic responses to environmental conditions on the one hand, and
carbon allocation to stem tissue on the other hand. Variability in the isotopic ratio
largely responded to summer climate, but was weakly correlated to annual stem
growth. In contrast, climate sensitivity of radial growth in both species was rather
site-dependent, and was strongest at the driest (in terms of soil water capacity)
site.
We will also present results of isotope responses with respect to extreme climate
events.
Understanding the underlying physiological mechanisms controlling the short-term
variation in tree-ring signals will help to assess and more precisely constrain the possible
range of growth performance of these ecologically and economically important tree species
under future climate conditions.
This project is funded by the Swiss National Science Foundation Foundation, Project
iTREE no. CRSII3_136295. |
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