Spatiotemporal dynamic of European beech (Fagus sylvatica L.) in Slovenia, 1970–2005

Based on data acquired from the spatial information system Silva-SI, the majority of the entire forest area in Slovenia (22,220 forest compartments with a total area of 7446 km2, classified into eight forest categories) was analysed for changes in the distribution of European beech (Fagus sylvatica L.) in the period 1975–2005 using a binary logistic regression model in terms of selected site, stand and management variables. Additionally, changes in the abundance of beech in forest stands in which beech was present at the beginning and the end of the analysed period were analysed. Beech expanded its area by more than 1200 ha per year on average, i.e. the annual expansion rate amounted to 0.24%. Among the 18 studied variables, three site, four stand and no management variables were included in the binary logistic regression model of beech expansion. Beech expansion was more pronounced at lower altitudes, on sites with steep topography, and on sites with a higher proportion of beech in potential natural vegetation. The probability of beech expansion reduced by a factor of 0.54 when the distance to the nearest compartment with beech increased by 1 km. Among other stand variables, the proportion of early successional phases and the proportion of silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) Karst.) also influenced the expansion of beech. During the observed period the growing stock of beech almost doubled, its proportion in total growing stock increasing from 27% to 32%. Significant differences were found in changes of beech proportion in the total growing stock among different forest categories; a decrease in the beech proportion was registered in alpine coniferous forests and thermophilous deciduous forests, while in other forest categories the proportion of beech increased. The recent development of forest stands and their current structure indicate a further expansion of beech and an increase in the proportion of beech in forest stands.