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| Titel |
Analysing Amazonian forest productivity using a new individual and trait-based model (TFS v.1) |
| VerfasserIn |
N. M. Fyllas, E. Gloor, L. M. Mercado, S. Sitch, C. A. Quesada, T. F. Domingues, D. R. Galbraith, A. Torre-Lezama, E. Vilanova, H. Ramírez-Angulo, N. Higuchi, D. A. Neill, M. Silveira, L. Ferreira, G. A. Aymard C., Y. Malhi, O. L. Phillips, J. Lloyd |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 4 ; Nr. 7, no. 4 (2014-07-03), S.1251-1269 |
| Datensatznummer |
250115653
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1251-2014.pdf |
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| Zusammenfassung |
| Repeated long-term censuses have revealed large-scale spatial patterns in
Amazon basin forest structure and dynamism, with some forests in the west of
the basin having up to a twice as high rate of aboveground biomass
production and tree recruitment as forests in the east. Possible causes for
this variation could be the climatic and edaphic gradients across the basin
and/or the spatial distribution of tree species composition. To help
understand causes of this variation a new individual-based model of tropical
forest growth, designed to take full advantage of the forest census data
available from the Amazonian Forest Inventory Network (RAINFOR), has been
developed. The model allows for within-stand variations in tree size
distribution and key functional traits and between-stand differences in
climate and soil physical and chemical properties. It runs at the stand
level with four functional traits – leaf dry mass per area (Ma), leaf
nitrogen (NL) and phosphorus (PL) content and wood density
(DW) varying from tree to tree – in a way that replicates the observed
continua found within each stand. We first applied the model to validate
canopy-level water fluxes at three eddy covariance flux measurement sites.
For all three sites the canopy-level water fluxes were adequately simulated.
We then applied the model at seven plots, where intensive measurements of
carbon allocation are available. Tree-by-tree multi-annual growth rates
generally agreed well with observations for small trees, but with deviations
identified for larger trees. At the stand level, simulations at 40 plots
were used to explore the influence of climate and soil nutrient availability
on the gross (ΠG) and net (ΠN) primary production rates
as well as the carbon use efficiency (CU). Simulated ΠG, ΠN and CU were not associated with
temperature. On the other hand, all three measures of stand level
productivity were positively related to both mean annual precipitation and
soil nutrient status. Sensitivity studies showed a clear importance of an
accurate parameterisation of within- and between-stand trait variability on
the fidelity of model predictions. For example, when functional tree
diversity was not included in the model (i.e. with just a single plant
functional type with mean basin-wide trait values) the predictive ability of
the model was reduced. This was also the case when basin-wide (as opposed to
site-specific) trait distributions were applied within each stand. We
conclude that models of tropical forest carbon, energy and water cycling
should strive to accurately represent observed variations in functionally
important traits across the range of relevant scales. |
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