Acclimation to high irradiance in temperate deciduous trees in the field: changes in xanthophyll cycle pool size and in photosynthetic capacity along a canopy light gradient

arbre forestier betula pendula canopy chemical composition composition chimique couvert cubierta de copas electron transfer fisiologia vegetal foliage forest trees light luz ombre oxidoreductions photosynthese photosynthesis pigment pigmentos pigments plant physiology populus tremula shade shade tolerance sombra tilia cordata xanthophylle xanthophylls xantofilas