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| Titel |
Response of carbon fluxes to water relations in a savanna ecosystem in South Africa |
| VerfasserIn |
W. L. Kutsch, N. Hanan, B. Scholes, I. McHugh, W. Kubheka, H. Eckhardt, C. Williams |
| 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 ; 5, no. 6 ; Nr. 5, no. 6 (2008-12-23), S.1797-1808 |
| Datensatznummer |
250002942
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| Publikation (Nr.) |
 copernicus.org/bg-5-1797-2008.pdf |
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| Zusammenfassung |
The principal mechanisms that connect carbon fluxes with water relations in
savanna ecosystems were studied by using eddy covariance method in a savanna
ecosystem at Kruger National Park, South Africa. Since the annual drought
and rewetting cycle is a major factor influencing the function of savanna
ecosystems, this work focused on the close inter-connection between water
relations and carbon fluxes. Data from a nine-month measuring campaign
lasting from the early wet season to the late dry season were used.
Total ecosystem respiration showed highest values at the onset of the
growing season, a slightly lower plateau during the main part of the growing
season and a continuous decrease during the transition towards the dry
season.
The regulation of canopy conductance was changed in two ways: changes due to
phenology during the course of the growing season and short-term acclimation
to soil water conditions.
The most constant parameter was water use efficiency that was influenced by
VPD during the day but the VPD response curve of water usage did change only
slightly during the course of the growing season and decreased by about 30%
during the transition from wet to dry season.
The regulation of canopy conductance and photosynthetic capacity were
closely related. This observation meets recent leaf-level findings that
stomatal closure triggers down-regulation of Rubisco during drought. Our
results may show the effects of these processes on the ecosystem scale. |
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