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| Titel |
Stable C and O Isotopes from Tree Rings Reveal Changes in the Carbon Water Relations Along a Siberian North South Transect in the Last 150 Years |
| VerfasserIn |
Rolf T. W. Siegwolf, Olga V. Sidorova, Matthais Saurer, Alexander Kirdyanov, Anastasia A. Knorre, Eugene A. Vaganov |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039980
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| Zusammenfassung |
| The increasing industrialization in the last 150 years resulted an increasing atmospheric CO2
concentration (ca) from ca. 260 to 385 ppm as a result of the growing use of fossil fuels.
Besides the greenhouse effect elevated CO2 affects also the vegetation, as plants respond
instantaneously with an increased photosynthetic rate, and a reduction in stomatal
conductance. This results in a lower ci/caratio (ci is the leaf intercellular CO2 concentration),
which is reflected in a reduced 13C fractionation during photosynthesis. Accordingly the
intrinsic water use efficiency (WUEi) will be altered. However, with increasing
duration of exposure to elevated CO2 plants will acclimatize, i.e. down regulate
the photosynthetic capacity to some degree. The degree of the long-term response
to changes in CO2 varies largely between plants growing under different growth
conditions, such as climate water availability, nutrient supply and between different
species.
In this presentation we show C and O isotope data from tree rings for the last 150 years,
reflecting the changes in the carbon water relations (WUEi) from central Siberia (Russia)
along a north south transect of ca. 2400 km. It will be shown that changes in the environment
either increase or reduce the effect of elevated CO2 on trees, growing in the highly sensitive
Siberian ecosystem. The combination of the C and O isotope fractionation values in a
conceptual model (Scheidegger et al., 2000; Saurer and Siegwolf, 2007) allows the
link of gas exchange mechanisms with δ13C and δ18O data. With this conceptual
approach we can distinguish whether trees respond to elevating CO2 and environmental
changes with an increase in the photosynthetic rate or with changes in the stomatal
conductance or both. The understanding of the physiological response patterns of trees to
elevated CO2 allows an improved interpretation of climate data for the last 150
years.
Matthias Saurer, Rolf T.W. Siegwolf, 2007. Human impacts on tree ring growth
reconstructed from stable isotopes. In: Stable Isotopes as Indicators of Ecological Change.
Todd E. Dawson, R.T.W. Siegwolf. (Eds.), Terrestrial Ecology Series, Elsevier; Amsterdam,
Boston, pp. 49-62.
Scheidegger Y., M. Saurer, M. Bahn and Siegwolf RTW, (2000). Linking stable oxygen
and carbon isotopes with stomatal conductance and photosynthetic capacity: a conceptual
model. Oecologia, 125 (3): 350-357. |
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