Stem growth and epicormic branch formation in understorey beech trees (Fagus sylvatica L.)

A study of the formation of epicormic branches on suppressed beech trees re vealed developmental sequences that had not hitherto been studied in depth. By combining architectural analysis and anatomy, it was possible to trace the history of the plant and thus fully understand the ontogenesis of the i ndividuals studied. The main sequences observed were: (1) the formation of moribund trees that were gradually covered in epicormic branches from the b ase of the stem to the crown following gradual forest closure; (2) the form ation of this new crown of epicormic branches was combined with a very shar p reduction in stem cambial activity (partial rings, if any) and modificati ons to the ligneous sections; and (3) resumed girth increment following the establishment of epicormic branches. After describing in detail the method s and individual variation, we highlight the spatial and temporal patterns of the phenomena observed. Lastly, we put forward functional hypotheses wit h a view to setting these results against a background of forest tree ontog enesis in general. (C) 2001 Annals of Botany Company.