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.
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 stem 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(t) and stem diameter increment, decreased over time as a result of a relative decrease in the proportion of photosynthetic tissues to total sapling biomass.
Balandier
Philippe
P
Cemagref of Clermont-Ferrand, Team of Applied Ecology of Woodlands, 24 avenue des Landais, BP 50085, F-63172 Aubière cedex, France. philippe.balandier@cemagref.fr
Sinoquet
Herve
H
Frak
Ela
E
Giuliani
Rita
R
Vandame
Marc
M
Descamps
Sylvestre
S
Coll
Lluis
L
Adam
Boris
B
Prevosto
Bernard
B
Curt
Thomas
T
D002241:Carbohydrates / Q000096:biosynthesis*; D002244:Carbon / Q000378:metabolism; D029964:Fagus / Q000254:growth & development* / Q000378:metabolism; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D041605:Pinus sylvestris / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism; D014197:Trees / Q000254:growth & development* / Q000378:metabolism
D002241:Carbohydrates; D002244:Carbon