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| Titel |
Biophsyical constraints on gross primary production by the terrestrial biosphere |
| VerfasserIn |
H. Wang, I. C. Prentice, T. W. Davis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 20 ; Nr. 11, no. 20 (2014-10-31), S.5987-6001 |
| Datensatznummer |
250117661
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| Publikation (Nr.) |
 copernicus.org/bg-11-5987-2014.pdf |
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| Zusammenfassung |
| Persistent divergences among the predictions of complex carbon-cycle models
include differences in the sign as well as the magnitude of the response of
global terrestrial primary production to climate change. Such problems with
current models indicate an urgent need to reassess the principles underlying
the environmental controls of primary production. The global patterns of
annual and maximum monthly terrestrial gross primary production (GPP) by
C3 plants are explored here using a simple first-principles model based
on the light-use efficiency formalism and the Farquhar model for C3
photosynthesis. The model is driven by incident photosynthetically active
radiation (PAR) and remotely sensed green-vegetation cover, with additional
constraints imposed by low-temperature inhibition and CO2 limitation.
The ratio of leaf-internal to ambient CO2 concentration in the model
responds to growing-season mean temperature, atmospheric dryness (indexed by
the cumulative water deficit, Δ E) and elevation, based on an optimality
theory. The greatest annual GPP is predicted for tropical moist forests, but
the maximum (summer) monthly GPP can be as high, or higher, in boreal or
temperate forests. These findings are supported by a new analysis of CO2
flux measurements. The explanation is simply based on the seasonal and
latitudinal distribution of PAR combined with the physiology of
photosynthesis. By successively imposing biophysical constraints, it is shown
that partial vegetation cover – driven primarily by water shortage –
represents the largest constraint on global GPP. |
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