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Évaluation de la vulnérabilité de la forêt méditerranéenne face à une sécheresse accrue. Rapport final du projet DROUGHT+

Abstract : On-going changes in the Mediterranean climate are reducing rain amounts and modifying their distribution pattern. How does anticipate the effects of such changes on ecosystem functions? We retained two dominant evergreen tree species with contrasted responses to water limitation: the broadleaved Quercus ilex and the needle leaved Pinus halepensis. We used two long-term highly instrumented sites embedded with ecosystem manipulation experiments simulating partial to total rain exclusions and watering, and two transects of 4 sites, along a gradient of increasing aridity, on both side of the main sites. In the partial exclusions, the species displayed physiological responses showing acclimation for functional traits associated with carbon assimilation and water transport. It appears difficult when comparing these results with those from the gradients to separate acclimation to adaptation effects. Changes in branch architecture seem a good mean for the tree to undergo more severe water limitation. As the consequence we observed a decline in the transpirating leaf area on both tree species but the underlying mechanisms are still unknown. These architectural changes limited the vulnerability of such species to climate changes. At ecosystem scale the responses were complicated by intricate mechanisms working at contrasted time scales. The slight changes with C fluxes and particularly for ecosystem respiration we observed may be explained by slow changes in soil C pools, microbial activities and ectomycorhizal communities.
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https://hal.inrae.fr/hal-02595600
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Submitted on : Friday, May 15, 2020 - 8:11:52 PM
Last modification on : Monday, March 29, 2021 - 1:54:02 PM

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  • IRSTEA : PUB00032858

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Serge Rambal, Laurent Misson, Roland Huc, M. Vennetier, F. Guibal, et al.. Évaluation de la vulnérabilité de la forêt méditerranéenne face à une sécheresse accrue. Rapport final du projet DROUGHT+. [Rapport de recherche] irstea. 2011, pp.27. ⟨hal-02595600⟩

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