 |
| Titel |
Modelling basin-wide variations in Amazon forest productivity – Part 1: Model calibration, evaluation and upscaling functions for canopy photosynthesis |
| VerfasserIn |
L. M. Mercado, J. Lloyd, A. J. Dolman, S. Sitch, S. Patiño |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-28), S.1247-1272 |
| Datensatznummer |
250003912
|
| Publikation (Nr.) |
 copernicus.org/bg-6-1247-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
Given the importance of Amazon rainforest in the global carbon and
hydrological cycles, there is a need to parameterize and validate
ecosystem gas exchange and vegetation models for this region in order
to adequately simulate present and future carbon and water
balances. In this study, a sun and shade canopy gas exchange model is
calibrated and evaluated at five rainforest sites using eddy
correlation measurements of carbon and energy fluxes.
Results from the model-data evaluation suggest that with adequate
parameterisation, photosynthesis models taking into account the
separation of diffuse and direct irradiance and the dynamics of sunlit
and shaded leaves can accurately represent photosynthesis in these
forests. Also, stomatal conductance formulations that only take into
account atmospheric demand fail to correctly simulate moisture and
CO2 fluxes in forests with a pronounced dry season, particularly
during afternoon conditions. Nevertheless, it is also the case that
large uncertainties are associated not only with the eddy correlation
data, but also with the estimates of ecosystem respiration required
for model validation. To accurately simulate Gross Primary
Productivity (GPP) and energy partitioning the most critical
parameters and model processes are the quantum yield of photosynthetic
uptake, the maximum carboxylation capacity of Rubisco, and simulation
of stomatal conductance.
Using this model-data synergy, we developed scaling functions to
provide estimates of canopy photosynthetic parameters for a range of
diverse forests across the Amazon region, utilising the best fitted
parameter for maximum carboxylation capacity of Rubisco, and foliar
nutrients (N and P) for all sites. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|