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| Titel |
How drought severity constrains gross primary production(GPP) and its partitioning among carbon pools in a Quercus ilex coppice? |
| VerfasserIn |
S. Rambal, M. Lempereur, J. M. Limousin, N. K. Martin-StPaul, J. M. Ourcival, J. Rodríguez-Calcerrada |
| 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. 23 ; Nr. 11, no. 23 (2014-12-09), S.6855-6869 |
| Datensatznummer |
250117721
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| Publikation (Nr.) |
 copernicus.org/bg-11-6855-2014.pdf |
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| Zusammenfassung |
| The partitioning of photosynthates toward biomass compartments plays a crucial
role in the carbon (C) sink function of forests. Few studies have examined how
carbon is allocated toward plant compartments in drought-prone forests. We
analyzed the fate of gross primary production (GPP) in relation to yearly water deficit in an old
evergreen Mediterranean Quercus ilex coppice severely affected by
water limitations. Carbon fluxes between the ecosystem and the atmosphere
were measured with an eddy covariance flux tower running continuously since
2001. Discrete measurements of litterfall, stem growth and fAPAR
allowed us to derive annual productions of leaves, wood, flowers and acorns,
and an isometric relationship between stem and belowground biomass has been
used to estimate perennial belowground growth. By combining eddy covariance
fluxes with annual net primary productions (NPP), we managed to close a C budget and
derive values of autotrophic, heterotrophic respirations and carbon-use
efficiency (CUE; the ratio between NPP and GPP). Average values of yearly
net ecosystem production (NEP), GPP and Reco were 282, 1259 and 977 g C m−2. The
corresponding aboveground net primary production (ANPP) components were 142.5, 26.4 and 69.6 g C m−2 for
leaves, reproductive effort (flowers and fruits) and stems, respectively. NEP, GPP and
Reco were affected by annual water deficit. Partitioning to the
different plant compartments was also impacted by drought, with a hierarchy
of responses going from the most affected – the stem growth – to the least
affected – the leaf production. The average CUE was 0.40, which is well in the
range for Mediterranean-type forest ecosystems. CUE tended to decrease less drastically in response to drought than GPP and NPP did, probably due to
drought acclimation of autotrophic respiration. Overall, our results provide
a baseline for modeling the inter-annual variations of carbon fluxes and
allocation in this widespread Mediterranean ecosystem, and they highlight the value
of maintaining continuous experimental measurements over the long term. |
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