Long-term use of uneven-aged silviculture in mixed mountain Dinaric forests: a comparison of old-growth and managed stands

In recent years there has been growing interest in the silviculture of uneven-aged forests because of their resilience and stability in an increasingly changing environment. However, some studies have indicated that strict adherence to selection systems results in the homogenization of forest structure. We studied the composition and structure of four mixed European silver fir – European beech mountain forests managed by an uneven-aged system and compared the results with four old-growth forests in the vicinity. A network of permanent inventory plots was installed in all research sites, and the structural attributes of the forest stands were estimated. We used data derived from LIDAR sampling for analyses of vertical structure. In old-growth stands tree density, canopy gap area and light levels were lower, while basal area, mean tree dbh and the density of large-diameter trees were higher. The variability of tree density, basal area and light conditions were lower in the old-growth stands. Several independent analyses indicated increasing dominance and a more pronounced past and predicted future increase in the relative abundance of beech in old-growth forests when compared with managed forests. The results indicate that the persistence of shade-tolerant and mid-tolerant tree species in managed forests may be due to the interaction of variable regeneration fellings and consistent favouring of crop trees.