Regeneration dynamics in an alluvial dense ash (Fraxinus excelsior L.) stand

Broadleaves  regeneration dynamics and the succession mechanism were studied within  a    transect of 14 m x 56 m in a dense 80-year-old ash stand situated on an  alluvial soil. For this    purpose, abundance and height of all naturally regenerated species at  different development    stages were analyzed and their distribution over the juvenile and older  growth stages    determined.    The study reveals that from the main broadleaved tree species, Quercus robur and Fagus    sylvatica regeneration scarcely occur at any  growth stages. No Fraxinus excelsior regeneration,    except 1 unit, taller than sapling (1.5-4 m) can be found on this soil  type. On the contrary, Acer    pseudoplatanus represents different development  stages (seedling, sapling, thicket, small pole    and large pole) and in stand patches where an understorey is practically  lacking, its    regeneration is well developed. Results generally show that at the juvenile  and older growth    stages Acer proceeds Fraxinus and regeneration is largely  dominated by the invasive Acer. It is    expected that this succession process will continue and that Acer will overcome in the    overstorey and even gradually form an almost single-species dominating  stage. Direct    interventions are unavoidable in order to regulate the primary mixture  patterns.