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- Title
Effect of land use on carbon dioxide, water vapour and energy exchange over terrestrial ecosystems in Southwestern France during the CERES campaign.
- Authors
Jarosz, N.; Béziat, P.; Bonnefond, J. M.; Brunet, Y.; Calvet, J. C.; Ceschia, E.; Elbers, J. A.; Hutjes, R. W.A.; Traullé, O.
- Abstract
Eddy fluxes were measured over different ecosystems, winter and summer crops, a maritime pine forest at different stages of development and grassland, from 17 May to 26 June 2005 in the southwestern region of France. During the experiment, summer crops started growing whereas winter crops and grassland achieved their senescence. Comparatively, the other ecosystems had a much slower growth emphasized by soil water deficit at forest sites. The ten ecosystems showed different partitioning of available energy. Net radiation was the highest above the maritime pine forest, followed, in decreasing order, by the crops, the vineyard and the grassland. Over the whole campaign period, the Bowen ratio (β=H/LE) was larger above the forest sites than for the other sites. The various vegetation types also showed contrasting net ecosystem exchange (NEE) dynamics following their growth status and respective behaviour in response to drought. Both the clearcut and summer crops before irrigation and plant growth be haved as sources of CO2, whereas the vineyard, the mature forest and winter crops acted as sinks. However the maize crops became substantial sinks of CO2 after the start of irrigation and canopy growth, with fluxes twice as large as for the mature pine forest. Finally, throughout the experiment, forest, grassland and crops sequestrated from about 50 gCm-2 to 230 gCm-2, while the cleacut and the beans crop rejected about 30 gCm-2. These results support the idea that converting a mature forest to a clearcut or bare soil available to agricultural use enhances the sensible heat flux and shifts the ecosystem from a sink to a source of carbon.
- Subjects
SOUTHWESTERN France; LAND use; CARBON dioxide; ATMOSPHERIC water vapor; EDDY flux; ENERGY transfer; SOIL moisture; HEAT flux
- Publication
Biogeosciences Discussions, 2009, Vol 6, Issue 2, p2755
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-6-2755-2009