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Ecophysiologie et réaction à la sécheresse de trois espèces de conifères (Abies alba Miller, Picea abies (L.) Karsten et Pinus sylvestrisS L.) : effet de l'âge

Abstract : Water relations and gas exchange of 3 conifer species (seedlings, saplings and adult trees) were examined under controlled and/or natural conditions. Under controlled conditions, measurement on 9 month old seedlings showed that Abies alba had weak stomatal control when subjected to soil drought, while Pinus sylvestris and Picea abies exhibited a stronger stomatal sensitivity to drought. For 5-6 year old saplings, differences between these species were not significant. The passage from seedling stage to sapling stage increased the gas exchange rate for Picea abies and Pinus sylvestris, the inverse was found for Abies alba. Water transfer in the trees was assessed in an adult stand of Picea abies in the Vosges (NE France). Transpiration fell from 60% to 10% of Penman?s evapotranspiration while the predawn water potential decreased from -0.5 to -1.0 MPa. Whole-tree hydraulic conductance calculated from diurnal sap flow and twig water potential measurements also showed an important decrease during this dry period. Partitioning of whole-tree hydraulic conductance and measurement of xylem embolism in the twigs showed that the major modification of water movement in the soil-leaves pathway was at the soil-root interface. No embolism was detected for these trees in spite of a severe drought.
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https://hal.univ-lorraine.fr/tel-01747385
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Ping Lu. Ecophysiologie et réaction à la sécheresse de trois espèces de conifères (Abies alba Miller, Picea abies (L.) Karsten et Pinus sylvestrisS L.) : effet de l'âge. Biologie végétale. Université Henri Poincaré - Nancy 1, 1992. Français. ⟨NNT : 1992NAN10339⟩. ⟨tel-01747385⟩

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