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| Titel |
Simultaneous measurements of CO2 and water exchanges over three agroecosystems in South-West France |
| VerfasserIn |
P. Stella, E. Lamaud, Y. Brunet, J.-M. Bonnefond, D. Loustau, M. Irvine |
| 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 ; 6, no. 12 ; Nr. 6, no. 12 (2009-12-11), S.2957-2971 |
| Datensatznummer |
250004224
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| Publikation (Nr.) |
 copernicus.org/bg-6-2957-2009.pdf |
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| Zusammenfassung |
| During the last few decades, many studies have been performed to determine
water and carbon budgets of broadleaf and deciduous forests, crops and
grasslands. However, since most measurements have been made in different
regions and at different periods, it is difficult to compare the results
directly. In order to evaluate accurately the respective contribution of
various agroecosystems to global water and carbon exchanges, it is necessary
to compare data obtained in similar climatic and weather conditions. To
address this question, we present the results from simultaneous measurements
carried out during one year over three typical agroecosystems of the Les
Landes region in South-West France:~an agricultural field with maize from 29
May to 18 October, a young (5 year-old) pine forest and a mature (37
year-old) pine forest. All measurements were collected as part of the
Regional Experiment component of the CarboEurope-IP project. During most of
the year, the agricultural field without vegetation is a source of CO2,
but from late June to early September the maize crop becomes a stronger
carbon sink than the forests. Over the whole measurement period the three
agroecosystems behave as CO2 sinks with carbon storage of about 335,
210 and 160 g C m−2 for the young forest, the mature forest and the
agricultural field, respectively. We investigated the influence of climatic
conditions on Gross Primary Production (GPP) of the three ecosystems and
observed a predominant role of vapour pressure deficit (VPD) for forests and
of photosynthetic photon flux density (FPP) for maize. Daily Water Use
Efficiencies (WUE) of the three ecosystems were evaluated and expressed as
functions of the mean daily vapour pressure deficit (VPD). Similar trends
were observed for the two forests, which suggests that for a given species
WUE is independent of stand age. The WUE of the maize crop at maturity was
also found to depend upon VPD, but it is about twice as large as for the
forests, owing to the physiological advantages of C4 species. |
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