Seasonal wood formation dynamics of beech (Fagus sylvatica L.) and black locust (Robinia pseudoacacia L.) as determined by the "pinning" technique

We investigated the dynamic process of wood formation in the diffuse-porous beech and the ring-porous black locust using the so-called pinning techniq ue. The histological alterations in the cambial zone caused by this techniq ue were illustrated by light and electron microscopy. Wood formation began in beech in the second week of May after bud break and in black locust in t he first week of May before bud break and ended in both species in the seco nd week of September. In beech, radial increment was slow at the beginning, fast thereafter, and slow again towards the end of the vegetation period. In black locust, radial increment was fast during the first weeks and then gradually declined to zero.