Natural stand changes in the forest reserve of Liedekerke were analysed during the period 1986-1996, using a permanent grid of circular plots. The monitoring concentrated on natural changes in species composition, using stem number and basal area as indicators, and changes in spatial distribution and colonization capacities of trees and shrubs, with special interest in the competition between exotic and indigenous species. After only a decade of monitoring important natural changes in the woody layer were detected. The pioneer forest is gradually maturing through self-thinning processes and shifts in species composition. The overall stem number decreased with 33.6%, while the basal area increased with 20.9%. Birch (Betula pendula/ pubescens) and indigenous oak (Quercus robur/petraea) remained dominant. More tolerant exotic species, like red oak (Quercus rubra) and sweet chestnut (Castanea sativa), are slowly increasing their share in the species composition and expanding their range. Pioneer species on the other hand, like aspen (Populus tremula), willow (Salix capreaicinerealaurita), alder buckthorn (Frangula alnus) and common (Alnus glutinosa) and grey alder (A. incana), strongly declined. Black cherry (Prunus serotina) seems to be slowly invading the forest due to its massive natural regeneration. Strong competition may be expected especially from rowan ash (Sorbus aucuparia), which showed similar regeneration and colonization capacities. Elder (Sambucus nigra) dramatically extented its range, though its share remains marginal. Beech remained absent most probably due to the lack of mature trees in the vacinity of the forest. Finally this change detection allowed that general predictions could be made on the future natural development and composition of this forest reserve, which could serve forest management decisions.
Stem Photosynthesis not Pressurized Ventilation is Responsible for Light-enhanced Oxygen Supply to Submerged Roots of Alder (Alnus glutinosa)
