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

Abstract

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.