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| Titel |
On the limits and capability of modeling water, energy and carbon fluxes in deciduous forest exposed to elevated CO2 |
| VerfasserIn |
Simone Fatichi, Sebastian Leuzinger |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076502
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| Zusammenfassung |
| Understanding future patterns of carbon cycle is strongly connected to forest behavior in an
atmosphere with increasing CO2. Observations in mature, steady-state forests are logistically
challenging and difficult to upscale, therefore most of our experimental knowledge is derived
from results obtained for young trees or homogenous stands. A combination of numerical
modeling and observations can complement our knowledge on the behavior of
heterogeneous forests where the leaf-level photosynthetic response to elevated CO2
typically does not translate into a proportional increase in plant growth. We compare
data from a free air CO2 enrichment (FACE) experiment in a mature deciduous
forest in Switzerland with realizations from a state-of-the-art ecohydrological model
(Tethys-Chloris). Model realizations compare favorably with field observations of
photosynthesis, stomatal conductance, sap flow, leaf and fruit litter, and stem growth.
The model captures the observed CO2-induced difference in transpiration and its
sensitivity to atmospheric demand, as well as qualitative changes in soil moisture.
The simulated differences between CO2 scenarios for both the carbon and water
balance are generally less than 10% and fall within the uncertainty of experimental
observations. Simulated allocation to stem growth is c. 50 gC yr-1 m-2 higher
in the modeled CO2 scenario, which is within the uncertainty of stand upscaled
observations. These results demonstrate that while ecohydrological models can be used
to reliably simulate multi-year energy, water, and carbon fluxes, evaluating the
modeled carbon allocation remains critical. Simplified and rather empirical carbon
allocation rules used in the model cannot be confirmed or rejected given the current
accuracy of field measurements. Despite such uncertainties we conclude that, taken
together both modeling and experimental results, for this type of forest, ecosystem
responses to elevated CO2 in terms of energy and water fluxes are likely to be very
small. |
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