Architecture of Fagus sylvatica regeneration improves over time in mixed old-growth and managed forests

Basic dimensions and morphological characteristics of European beech (Fagus sylvatica L.) saplings were measured in an old-growth forest and in a selectively managed mixed Dinaric silver fir-beech forest in 2000 and 2005. Over the 5-year period, average relative diffuse radiation above saplings (DIF), sapling length, and root collar diameter significantly increased. Light proved to be an important factor influencing beech sapling crown architecture. There was a strong negative relation between plagiotropic sapling occurrence and DIF, while the relation between DIF and forked and broom-shaped crown forms was positive. Occurrence of all three crown irregularities was negatively related to the regeneration density. Crown plasticity was less expressed after the 5-year period of growth, as the number of plagiotropic, broom-shaped, and forked saplings decreased dramatically. The results of this study indicate that broom-shaped, forked, and plagiotropic trees did not recruit successfully, or that these types of morphological adaptations were no longer an advantage in the late sapling stage of development. The hypothesis that small-scale uneven-aged silvicultural systems, such as the selective system, result in poor beech regeneration architecture to the extent that the future quality of beech logs is affected was not confirmed by the results of this study.