Six-year time course of light-use efficiency, carbon gain and growth of beech saplings (Fagus sylvatica) planted under a Scots pine (Pinus sylvestris) shelterwood
2007
Balandier, Philippe | Sinoquet, Hervé | Frak, Ela | Giuliani, Rita | Vandame, Marc | Descamps, Sylvestre | Coll, Lluis | Adam, Boris, B. | Prevosto, Bernard | Curt, Thomas | Écosystèmes forestiers (UR EFNO) ; Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF) | Laboratoire de Physique et Physiologie Intégratives de l'Arbre Fruitier et Forestier (PIAF) ; Institut National de la Recherche Agronomique (INRA)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP) | Unité de recherche d'Écophysiologie des Plantes Fourragères (UEPF) ; Institut National de la Recherche Agronomique (INRA) | Dipartamento di Colture Arboree ; Alma Mater Studiorum Università di Bologna = University of Bologna (UNIBO) | Centre de Ciència i Tecnologia Forestal de Catalunya (CTFC) | Ecosystèmes méditerranéens et risques (UR EMAX) ; Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)
Two-year-old Fagus sylvatica L. saplings were planted under the cover of a Pinus sylvestris L. stand in the French Massif Central. The stand was differentially thinned to obtain a gradient of transmitted photosynthetically active radiation (PAR(t): 0-0.35). Eighteen Fagus saplings were sampled in this gradient, and their growth (basal stem diameter increment) was recorded over six years. Over the same period, morphological parameters (leaf area, number and arrangement in space) were monitored by 3D-digitization. Photosynthetic parameters were estimated with a portable gas-exchange analyzer. Photosynthesis was mainly related to light availability, whereas sapling morphology was mainly driven by sapling size. Annual stein diameter increment was related to the amount of light-intercepting foliage (silhouette to total leaf area ratio (STAR) x total sapling leaf area (LA)) and light availability above the saplings (PAR(t)). However, light-use efficiency. i.e.. the slope of the relationship between STAR x LA x PAR, and stem diameter increment, decreased over time as a result of a relative decrease in the proportion of photosynthetic tissues to total sapling biomass.
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