Due to a long history of intensive forest exploitation, few European beech (Fagus sylvatica L.) old-growth forests have been preserved in Europe. We studied two beech forest reserves in southern Slovenia. We examined the structural characteristics of the two forest reserves based on data from sample plots and complete inventory obtained from four previous forest management plans. To gain a better understanding of disturbance dynamics, we used aerial imagery to study the characteristics of canopy gaps over an 11-year period in the Kopa forest reserve and a 20-year period in the Gorjanci forest reserve. The results suggest that these forests are structurally heterogeneous over small spatial scales. Gap size analysis showed that gaps smaller than 500 m2 are the dominant driving force of stand development. The percentage of forest area in canopy gaps ranged from 3.2 to 4.5% in the Kopa forest reserve and from 9.1 to 10.6% in the Gorjanci forest reserve. These forests exhibit relatively high annual rates of coverage by newly established (0.15 and 0.25%) and closed (-0.08 and -0.16%) canopy gaps. New gap formation is dependant on senescent trees located throughout the reserve. We conclude that these stands are not even-sized, but rather unevenly structured. This is due to the fact that the disturbance regime is characterized by low intensity, small-scale disturbances.
Climatic changes affect minor resistance and vitality of the forest, incidence of natural disturbances increases. In this research we compared efficiency of natural and artificial restoration of forests affected by natural disturbances; the stress was laid on structure and growth of seedlings, impact of ground vegetation, and importance of seed trees. The first study compares success of regeneration according to three diverse treatments (1: preparation of soil, sowing, fencing; 2: sowing, fencing; 3: sowing and planting). In the second research we compared success of natural regeneration and artificial regeneration (planting) after windthrow. The results show that regeneration is positively affected by proximity of seed trees and soil preparation, while the impact of ground vegetation cover is negative. The densities of naturally grown seedlings on plots with natural regeneration surpass the ones on plots with artificial regeneration (disregarding planted seedlings).
In 2006 a hurricane blew down 125 ha of mostly mature even-aged spruce stands on the Jelovica plateau. Two post-windthrow inventories of regeneration were executed two and five years after the windthrow. Presence, abundance and composition of natural regeneration were surveyed on 81 plots of 16 m2 each. The proportion of plots without natural regeneration decreased from 30 % in 2008 to 11 % in 2011. The average abundance of regeneration was 7,955 individuals per hectare in 2008 and 9,660 individuals per hectare in 2011. In tree species composition spruce predominated with 46 %, but the proportion of broad leaves increased substantially in the observation period. Additionally, the impact of site and stand factors on regeneration was examined; influential factors of natural regeneration occurrence were investigated using a binary logistic regression, while influential factors of changes in regeneration density were examined using a generalized linear regression model. Among many influential factors, the analyses exposed the distance to the nearest stand, aspect/sun exposure, and the portion of leaf-litter on a plot.