It is well know that light requirements for significant growth increase with individual's size rather than with age for most young forest trees. We tested this assumption for the European beech (Fagus sylvatica), a particularly shade-tolerant species. Growth, crown morphology, light capture, photosynthesis and biomass allocation were recorded since beech plantation in 2000 in central France under the shelterwood of Pinus sylvestris thinned to get different light intensities. Beech growth rate increased with light availability with a plateau at 40-50%. The biomass shoot:root ratio was unaffected by light, whereas the ratio between leaf area and total plant biomass (LAR) logarithmically decreased with increasing light. This effect almost disappeared when taking into account individual biomass. It seems that the proportion of non-photosynthetic tissues (root, stem) increased faster than that of photosynthetic tissues (leaf). Therefore light availability to beech sapling should be continuously increased to maintain the same growth rate with time.