HR: 0800h
AN: B11A-0999    [Abstracts]
TI: Intra- and interspecific variability of carbon isotope composition (d13C) and water-use efficiency in 5 deciduous tree species growing a mixed stand in North-Eastern France
AU: * Zapater, M
EM: zapater@nancy.inra.fr
AF: INRA Nancy, Route de l'arboretum, CHAMPENOUX, 54 54280 France
AU: Breda, N
EM: breda@nancy.inra.fr
AF: INRA Nancy, Route de l'arboretum, CHAMPENOUX, 54 54280 France
AU: Storchi, G
EM: storchi@nancy.inra.fr
AF: INRA Nancy, Route de l'arboretum, CHAMPENOUX, 54 54280 France
AU: Granier, A
EM: agranier@nancy.inra.fr
AF: INRA Nancy, Route de l'arboretum, CHAMPENOUX, 54 54280 France
AB: Intra and interspecific variability in leaf gas exchange (net assimilation, stomatal conductance, transpiration, water use efficiency: WUE), in carbon isotope composition (d13C) and leaf characteristics related to photosynthesis was assessed in 5 trees species growing in a young broad-leaved mixed forest in North-Eastern France (Hesse, Lorraine). The studied species belong to contrasted functional groups of light tolerance: European beech (Fagus sylvatica) as shade tolerant species; sessile oak (Quercus petraea) and hornbeam (Carpinus betulus) as semitolerant species; silver birch (Betula pendula) and European aspen (Populus tremula) as shade intolerant species (pioneer species). Gas exchange was measured at leaf level in the upper and the lower canopy layers using a portable system (LI-6200, Licor). d13C signatures were determined in the sun and shade leaves in both bulk material and soluble sugars. Clear differences in bulk leaves and soluble sugars d13C and intrinsic WUEint were found among the investigated species, whatever the leaf location in the canopy. Within each tree species, shade leaves exhibited lower WUEint and more negative d13C than sun leaves. Little variability among trees was found for a given species. The 3 functional groups were separated by their leaf carbon content. Nevertheless each of the variables d13C, leaf mass area and nitrogen content, alone, could not separate the groups. A linear relationship was found between WUEint and d13C at the intraspecific level (r2 = 0.87 for leaves; r2 =0.89 for sugars) and at the interspecific level (r2 = 0.72 for bulk leaves). Nevertheless, this relationship differed from that of Farquhar et al. (1982), due to a different intercept, while the slope was the same. The causes of these variations are discussed. Key words: d13C; deciduous; mixed forest; WUEint; shade tolerance.
DE: 0410 Biodiversity
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005