title: 13C and 15N allocations of two alpine species from early and late snowmelt locations reflect their different growth strategies.
abstract: Intense efforts are currently devoted to disentangling the relationships between plant carbon (C) allocation patterns and soil nitrogen (N) availability because of their consequences for growth and more generally for C sequestration. In cold ecosystems, only a few studies have addressed whole-plant C and/or N allocation along natural elevational or topographical gradients. (12)C/(13)C and (14)N/(15)N isotope techniques have been used to elucidate C and N partitioning in two alpine graminoids characterized by contrasted nutrient economies: a slow-growing species, Kobresia myosuroides (KM), and a fast-growing species, Carex foetida (CF), located in early and late snowmelt habitats, respectively, within the alpine tundra (French Alps). CF allocated higher labelling-related (13)C content belowground and produced more root biomass. Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment. Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs. These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.
authors.affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université de Grenoble, BP 53, F-38041 Grenoble Cedex 09, France. florence.baptist@ujf-grenoble.fr
authors.forename: Florence
authors.initials: F
authors.lastname: Baptist
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tcherkez
authors.forename: Serge
authors.initials: S
authors.lastname: Aubert
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Pontailler
authors.forename: Philippe
authors.initials: P
authors.lastname: Choler
authors.forename: Salvador
authors.initials: S
authors.lastname: Nogués
mesh_terms: D001692:Biological Transport; D002247:Carbon Isotopes / Q000378:metabolism*; D003080:Cold Temperature; D029785:Cyperaceae / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D017753:Ecosystem; D005602:France; D009587:Nitrogen Isotopes / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes